Amoeba in Action

Sunday February 10, 2019

If your kitchen is like most kitchens, you probably have cabinets for cups and pots and pans, along with drawers for silverware and cooking utensils.  You might also have a drawer you call the “junk drawer.”  The things in this drawer aren’t actually “junk.”  If they were, you’d throw them away.  Instead, things usually get put here because they just don’t fit anywhere else.


You might be surprised to learn that the system for classifying organisms has its own “junk drawer.”  It’s called the protist kingdom.  Its members, like the contents of your kitchen junk drawer, are important, but don’t fit nicely in one of the other kingdoms.


Broadly, protists can be classified as animal-like, plant-like, or fungus-like.  It is important to remember that being “animal-like” does not make a protist an animal.  Such and organism, like plant-like or fungus-like protists, are members of an entirely different group of living things.


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Real Slime: Orange Bacteria

Sunday February 10, 2019

This type of slime Physarum Polycephalum is called the “many-headed slime”. This slime likes shady, cool, moist areas like you’d find in decaying logs and branches. Slime (or slime mold) is a word used to define protists that use spores to reproduce. (Note: Slime used to be classified as fungi.)


Real slime lives on microorganisms that inhabit dirt, grass, dead leaves, rotting logs, tropical fruits, air conditioners, gutters, classrooms and laboratories. Slime can grow to an area of several square meters.


Slime shows curious behaviors. It can follow a maze, reconnect itself when chopped in half, and predict whether an environment is good to live in or not. Scientists have battled with the ideas that at first glance, slime appears to be simply a “bag of amoebae”, but upon further study, seem to behave as if they have simple brains, like insects.


Slime can be either a plasmodial slime, a bag of cytoplasm containing thousands of individual nuclei, or a cellular slime which usually stays as individual unicellular protists until a chemical signal is released, causing the cells to gather and acts as one organism.
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How Bacteria Grow

Sunday February 10, 2019

All living things need a way to get energy. Bacteria get their food and energy in many ways. Some bacteria can make food on their own, while others need other organisms.


Some bacteria help other living things as they get energy, others hurt them while they get energy, and still others have no affect on living things at all.
Some living things, or organisms, are able to make their own food in a process called photosynthesis.


In this process, the organism turns energy from the sun into energy that can be used for energy. Organisms that get their energy from photosynthesis are called autotrophs. Some bacteria get their energy this way.


Some bacteria, called chemotrophs, get their energy by breaking down chemical compounds in the environment, including ammonia. Breaking down ammonia is important because ammonia contains the element nitrogen.


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Turning Compost into Gold

Sunday February 10, 2019

If you have a backyard garden, be sure to give it plenty of sunshine, water, and garbage.


Wait… garbage?  Yes, you read that right.


Garbage like rotting food and coffee grounds, made into compost, can be highly beneficial to garden plants.  Why? It all has to do with nitrogen.


Plants need nitrogen in order to survive.  There is plenty of nitrogen in the atmosphere; the problem is that plants can’t use it in the form found in the atmosphere.  For this, bacteria are needed.  Bacteria “fix” nitrogen, meaning that they change it into a usable form.


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Keep your compost heap moist, but not soggy and turn it with a pitchfork or spade to add air into the mix.  Once your compost bin is going strong, you can add it to your garden for improved plant growth!


Carnivorous Greenhouse

Sunday February 10, 2019

Plants need light, water, and soil to grow. If you provide those things, you can make your own greenhouse where you can easily observe plants growing. Here’s a simple experiment on how to use the stuff from your recycling bin to make your own garden greenhouse.


We’ll first look at how to make a standard, ordinary greenhouse. Once your plants start to grow, use the second part of this experiment to track your plant growth. Once you’ve got the hang of how to make a bottle garden, then you can try growing a carnivorous greenhouse.
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Eco-Column:

Sunday February 10, 2019

What grows in the corner of your windowsill? In the cracks in the sidewalk? Under the front steps? In the gutter at the bottom of the driveway? Specifically, how  doe these animals build their homes and how much space do they need? What do they eat? Where do fish get their food? How do ants find their next meal?


These are hard questions to answer if you don’t have a chance to observe these animals up-close. By building an eco-system, you’ll get to observe and investigate the habits and behaviors of your favorite animals. This column will have an aquarium section, a decomposition chamber with fruit flies or worms, and a predator chamber, with water that flows through all sections. This is a great way to see how the water cycle, insects, plants, soil, and marine animals all work together and interact.


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Predator-Prey: Who Eats Whom?

Sunday February 10, 2019

The way animals and plants behave is so complicated because it not only depends on climate, water availability, competition for resources, nutrients available, and disease presence but also having the patience and ability to study them close-up.


We’re going to build an eco-system where you’ll farm prey stock for the predators so you’ll be able to view their behavior. You’ll also get a chance to watch both of them feed, hatch, molt, and more! You’ll observe closely the two different organisms and learn all about the way they live, eat, and are eaten.


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Three Ways to Create a Plant

Sunday February 10, 2019

If you’ve ever eaten fruits or vegetables (and let’s hope you have), you have benefited from plants as food.  Of course, the plants we eat have been highly modified by growers to produce larger and sweeter fruit, or heartier vegetables.


There are three basic ways to create plants with new, more desirable traits:


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Building Speakers

Sunday February 10, 2019

Alexander Graham Bell developed the telegraph, microphone, and telephone back in the late 1800s. We’ll be talking about electromagnetism in a later unit, but we’re going to cover a few basics here so you can understand how loudspeakers transform an electrical signal into sound.


This experiment is for advanced students.We’ll be making different kinds of speakers using household materials (like plastic cups, foam plates, and business cards!), but before we begin, we need to make sure you really understand a few basic principles. Here’s what you need to know to get started:


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Rail Accelerator

Sunday February 10, 2019

We’re going to build on the quick ‘n’ easy DC motor to make a tiny rail accelerator (any larger, and you’ll need a power plant and a firing range and a healthy dose of ethics.) So let’s stick to the physics of what’s going on in this super-cool electromagnetism project. This project is for advanced students.


Here’s what we’re going to do:


We’re going to create two magnetic fields at right angles (perpendicular) to each other. When this happens, it causes things to move, spin, rotate, and roll out of the way. We’re going to focus this down to making a tiny set of wheel zip down a track powered only by magnetism. Ready?


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Hearing Magnetism

Sunday February 10, 2019

Want to hear your magnets? We’re going to use electromagnetism to learn how you can listen to your physics lesson, and you’ll be surprised at how common this principle is in your everyday life. This project is for advanced students.


We’re going to invert the ideas used when we created our homemade speakers into a basic microphone. Although you won’t be able to record with this microphone, it will show you how the basics of a microphone and amplifier work, and how to turn sound waves back into electrical signals. You’ll be using the amplifier and your spare audio plug from the Laser Communicator for this project.


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Homemade DC Motor

Sunday February 10, 2019

dcmotorImagine you have two magnets. Glue one magnet on an imaginary record player (or a ‘lazy susan’ turntable) and hold the other magnet in your hand. What happens when you bring your hand close to the turntable magnet and bring the north sides together?


The magnet should repel and move, and since it’s on a turntable, it will circle out of the way. Now flip your hand over so you have the south facing the turntable. Notice how the turntable magnet is attracted to yours and rotates toward your hand. Just as it reaches your hand, flip it again to reveal the north side. Now the glued turntable magnet pushes away into another circle as you flip your magnet over again to attract it back to you. Imagine if you could time this well enough to get the turntable magnet to make a complete circle over and over again… that’s how a motor works!


This next activity mystifies even the most scientifically educated! Here’s what you need:


Materials:


  • magnet
  • magnet wire (26g works well)
  • D cell battery
  • two paper clips (try to find the ones shown in the video, or else bend your own with pliers)
  • sandpaper
  • fat rubber band
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Relays & Homemade Shockers

Sunday February 10, 2019

relay-bigThis experiment is for advanced students. If you’ve attempted the relay and telegraph experiment, you already know it’s one of the hardest ones in this unit, as the gap needs to be *just right* in order for it to work. It’s a super-tricky experiment that can leave you frustrated and losing hope that you’ll ever get the hang of this magnetism thing.


Fear not, young scientist! Here’s a MUCH simpler relay experiment that will actually give a nice blue spark when fired up, along with a nice zap to the hand that touches it in just the right spot. You can also use this relay in your electricity experiments as a switch you can use to turn things on and off using electricity (instead of your fingers moving a switch), including how to make a latching burglar alarm circuit.


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Quick ‘n’ Easy DC Motor

Sunday February 10, 2019

Find a spare magnet – one you really don’t care about. Bring it up close to another magnet to find where the north and south poles are on the spare magnet. Did you find them? Mark the spots with a pen – put a N for north, and a S for south. Now break the spare magnet in half, separating the north from the south pole. (This might take a bit of muscle!) You should have one half be a north magnet, and the other a south. Or do you?


One of the big mysteries of the universe is why we can’t separate the north from the south end of a magnet. No matter how small you break that magnet down, you’ll still get one side that’s attracted to the north and the other that’s repelled. There’s just no way around this!


If you COULD separate the north from the south pole, you could point a magnet’s south pole toward your now-separated north pole, and it would always be repelled, no matter what orientation it rotated to. (Normally, as soon as the magnet is repelled, it twists around and lines up the opposite pole and snap! There go your fingers.) But if it were always repelled, you could chase it around the room or stick a pin through it so it would constantly move and rotate.


Well, what if we sneakily use electromagnetism? Note that you can use a metal screw, ball bearing, or other metal object that easily rotates.  If your metal ball bearing is also magnetic, you can combine both the screw and the magnet together.


Famous scientist Michael Faraday built the first one of these while studying magnetic and electricity, and how they both fit together. What to see what he figured out?


Here’s what you do:


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How Generators Work

Sunday February 10, 2019

Have you noticed that stuff sticks to your motor?  If you drag your motor through a pile of paperclips, a few will get stuck to the side. What’s going on?


Inside your motor are permanent magnets (red and blue things in the photo) and an electromagnet (the copper thing wrapped around the middle). Normally, you’d hook up a battery to the two tabs (terminals) at the back of the motor, and your shaft would spin.


However, if you spin the motor shaft with your fingers, you’ll generate electricity at the terminals. But how is that possible? That’s what this experiment is all about.


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Electromagnet

Sunday February 10, 2019

After you’ve completed the galvanometer experiment, try this one!


You can wrap wire around an iron core (like a nail), which will intensify the effect and magnetize the nail enough for you to pick up paperclips when it’s hooked up. See how many you can lift!


You can wrap the wire around your nail using a drill or by hand. In the picture to the left, there are two things wrong: you need way more wire than they have wrapped around that nail, and it does not need to be neat and tidy. So grab your spool and wrap as much as you can – the more turns you have around the nail, the stronger the magnet.


(We included this picture because there are so many like this in text books, and it’s quite misleading! This image is supposed to represent the thing you’re going to build, not be an actual photo of the finished product.)


Find these materials:


  • Batteries in a battery holder with alligator clip wires
  • A nail that can be picked up by a magnet
  • At least 3 feet of insulated wire (magnet wire works best but others will work okay)
  • Paper Clips
  • Masking Tape
  • Compass
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Galvanometers

Sunday February 10, 2019

Galvanometers are coils of wire connected to a battery. When current flows through the wire, it creates a magnetic field. Since the wire is bundled up, it multiplies this electromagnetic effect to create a simple electromagnet that you can detect with your compass.
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Ferrofluid

Sunday February 10, 2019

A ferrofluid becomes strongly magnetized when placed in a magnetic field. This liquid is made up of very tiny (10 nanometers or less) particles coated with anti-clumping surfactants and then mixed with water (or solvents). These particles don’t “settle out” but rather remain suspended in the fluid.


The particles themselves are made up of either magnetite, hematite or iron-type substance.


Ferrofluids don’t stay magnetized when you remove the magnetic field, which makes them “super-paramagnets” rather than ferromagnets. Ferrofluids also lose their magnetic properties at and above  their Curie temperature points.


Ferrofluids are what scientists call “colloidal suspensions”, which means that the substance has properties of both solid metal and liquid water (or oil), and it can change phase easily between the two. (We as show you this in the video below.) Because ferrofluids can change phases when a magnetic field is applied, you’ll find ferrofluids used as seals, lubricants, and many other engineering-related uses.


Here’s a video on toner cartridges and how to make your own homemade ferrofluid. It’s a bit longer than our usual video, but we thought you’d enjoy the extra content.


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Linear Accelerator

Sunday February 10, 2019

gauss-rifleThere are two ways to create a magnetic field. First, you can wrap wire around a nail and attach the ends of the wire to a battery to make an electromagnet. When you connect the battery to the wires, current begins to flow, creating a magnetic field. However, the magnets that stick to your fridge are neither moving nor plugged into the electrical outlet – which leads to the second way to make a magnetic field: by rubbing a nail with a magnet to line up the electron spin. You can essential “choreograph” the way an electron spins around the atom to increase the magnetic field of the material. This project is for advanced students.


There are several different types of magnets. Permanent magnets are materials that stay magnetized, no matter what you do to it… even if you whack it on the floor (which you can do with a magnetized nail to demagnetize it). You can temporarily magnetize certain materials, such as iron, nickel, and cobalt. And an electromagnet is basically a magnet that you can switch on and off and reverse the north and south poles.


The strength of a magnetic field is measured in “Gauss”. The Earth’s magnetic field measures 0.5 Gauss. Typical refrigerator magnets are 50 Gauss. Neodymium magnets (like the ones we’re going to use in this project) measure at 2,000 Gauss. The largest magnetic fields have been found around distant magnetars (neutron stars with extremely powerful magnetic fields), measuring at 10,000,000,000,000,000 Gauss. (A neutron star is what’s left over from certain types of supernovae, and typically the size of Manhattan.)


Linear accelerators (also known as a linac) use different methods to move particles to very high speeds. One way is through induction, which is basically a pulsed electromagnet. We’re going to use a slow input speed and super-strong magnets and multiply the effect to generate a high-speed ball bearing to shoot across the floor.


For this experiment, you will need:
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Curie Heat Engine

Sunday February 10, 2019
Marie Curie, a scientist famous for being the first person to receive two Nobel Prizes as well as her extensive work on radioactivity.

Magnetic material loses its ability to stick to a magnet when heated to a certain temperature called the Curie temperature. The Curie temperature for nickel is 380 oF, iron is 1,420oF, cobalt is 2,070 oF, and for ceramic ferrite magnets, it starts at 860oF.


We’re going to heat a magnet so that it loses temporarily loses its magnetic poles, and watch what happens as it cycles through cooling. Pierre and Marie Curie’s first scientific works were actually in magnetism, not chemistry, and their papers in magnetic fields and temperature when among the first noticed by the scientists at the time.


Are you ready to see what they figured out?


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Magnet Boats

Sunday February 10, 2019

We took our first step into the strange world of magnetism when we played with magnetizing a nail. We learned that magnets do what they do because of the behavior of electrons. When a bunch of those crazy little guys get going in the same direction they create a magnetic field. So what’s a magnetic field, you ask? That’s what this experiment is all about.


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Magnetic Sensors

Sunday February 10, 2019

reed-switchWouldn’t it be cool to have an alarm sound each time someone opened your door, lunch box, or secret drawer? It’s easy when you use a reed switch in your circuit! All you need to do it substitute this sensor for the trip wire and you’ll have a magnetic burglar alarm.


The first thing you need to do is get your reed switch out, because we have to tear into it in order to get the part we need.  Here’s what you need:


Materials:


  • reed switch
  • magnet
  • LED
  • AA case
  • 2 alligator wires
  • 2 AA batteries
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Magnetic Fields

Sunday February 10, 2019

This is a quick and simple experiment to answer the question of magnetic field strength: Do four magnets have a stronger magnetic pull than one? You’ll find the answer quite surprising… which is: it depends. Here’s what you need to do to see for yourself:


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Bouncing Magnets

Sunday February 10, 2019

Want to see a really neat way to get magnetic fields to interact with each other? While levitating objects is hard, bouncing them in invisible magnetic fields is easy. In this video, you’ll see how you can take two, three, or even four magnets and have them perform for you.


Are you ready?


Materials:


  • 3 identical magnets
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Flying Paper Clip

Sunday February 10, 2019

Have you ever been close to something that smells bad? Have you noticed that the farther you get from that something, the less it smells, and the closer you get, the more it smells? Well forces sort of work in the same way.


Forces behave according to a fancy law called the inverse-square law. To be technical, an inverse-square law is any physical law stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.


The inverse-square law applies to quite a few phenomena in physics. When it comes to forces, it basically means that the closer an object comes to the source of a force, the stronger that force will be on that object. The farther that same object gets from the force’s source, the weaker the effect of the force.


Mathematically we can say that doubling the distance between the object and the source of the force makes the force 1/4th as strong. Tripling the distance makes the force 1/9th as strong. Let’s play with this idea a bit.


Here’s what you need:


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Which way is North?

Sunday February 10, 2019

I can still remember in 2nd grade science class wondering about this idea. And I still remember how baffled my teacher was when I asked her this question: “Doesn’t the north tip of a compass needle point to the south pole?” Think about this – if you hold up a magnet by a string, just like the needle of a compass, does the north end of the magnet line up with the north or south pole of the earth?


If you remember about magnets, you know that opposite attract. So the north tip of the compass will line up with the Earth’s SOUTH pole. So compasses are upside-down! Here’s an activity you can do right now…
Materials:


  • magnet
  • compass
  • string
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Maxwell’s Second Equation

Sunday February 10, 2019

Maxwell’s Second Equation: All magnets have two poles. Magnets are called dipolar which means they have two poles. The two poles of a magnet are called north and south poles. The magnetic field comes from a north pole and goes to a south pole. Opposite poles will attract one another. Like poles will repel one another.


Materials: magnet you can break or cut in half, scissors or hammer (depending on the size of your magnet)


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Ten Static Electricity Experiments to Mystify Your Kids

Saturday February 9, 2019

Plasma ball centerThe smallest thing around is the atom, which has three main parts – the core (nucleus) houses the protons and neutrons, and the electron zips around in a cloud around the nucleus.


The proton has a positive charge, and the electron has a negative charge. In the hydrogen atom, which has one proton and one electron, the charges are balanced. If you steal the electron, you now have an unbalanced, positively charge atom and stuff really starts to happen. The flow of electrons is called electricity. We’re going to move electrons around and have them stick, not flow, so we call this ‘static electricity’.


These next experiments rely heavily on the idea that like charges repel and opposites attract. Your kids need to remember that these activities are all influenced by electrons, which are very small, easy to move around, and are invisible to the eye.
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Air Battery

Saturday February 9, 2019

dmmIt’s easy to use chemistry to generate electricity, once you understand the basics. With this experiment, you’ll use aluminum foil, salt, air, and a chemical from an aquarium to create an air battery. This experiment is for advanced students.


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Silver Battery

Saturday February 9, 2019

Never polish your tarnished silver-plated silverware again! Instead, set up a ‘silverware carwash’ where you earn a nickel for every piece you clean. (Just don’t let grandma in on your little secret!)


We’ll be using chemistry and electricity together (electrochemistry) to make a battery that reverses the chemical reaction that puts tarnish on grandma’s good silver.  It’s safe, simple, and just needs a grown-up to help with the stove.


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Salty Battery

Saturday February 9, 2019

Using ocean water (or make your own with salt and water), you can generate enough power to light up your LEDs, sound your buzzers, and turn a motor shaft. We’ll be testing out a number of different materials such as copper, aluminum, brass, iron, silver, zinc, and graphite to find out which works best for your solution.


This project builds on the fruit battery we made in Unit 8. This experiment is for advanced students.


The basic idea of electrochemistry is that charged atoms (ions) can be electrically directed from one place to the other. If we have a glass of water and dump in a handful of salt, the NaCl (salt) molecule dissociates into the ions Na+ and Cl-.


When we plunk in one positive electrode and one negative electrode and crank up the power, we find that opposites attract: Na+ zooms over to the negative electrode and Cl- zips over to the positive. The ions are attracted (directed) to the opposite electrode and there is current in the solution.


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Fruit Battery

Saturday February 9, 2019

This experiment shows how a battery works using electrochemistry. The copper electrons are chemically reacting with the lemon juice, which is a weak acid, to form copper ions (cathode, or positive electrode) and bubbles of hydrogen.


These copper ions interact with the zinc electrode (negative electrode, or anode) to form zinc ions. The difference in electrical charge (potential) on these two plates causes a voltage.


Materials:


  • one zinc and copper strip
  • two alligator wires
  • digital multimeter
  • one fresh large lemon or other fruit
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Electroplating

Saturday February 9, 2019

If you don’t have equipment lying around for this experiment, wait until you complete Unit 10 (Electricity) and then come back to complete this experiment. It’s definitely worth it!


Electroplating was first figured out by Michael Faraday. The copper dissolves and shoots over to the key and gets stuck as a thin layer onto the metal key. During this process, hydrogen bubbles up and is released as a gas. People use this technique to add material to undersized parts, for place a protective layer of material on objects, to add aesthetic qualities to an object.


Materials:


  • one shiny metal key
  • 2 alligator clips
  • 9V battery clip
  • copper sulfate (MSDS)
  • one copper strip or shiny copper penny
  • one empty pickle jar
  • 9V battery
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Electrolytes

Saturday February 9, 2019

When an atom (like hydrogen) or molecule (like water) loses an electron (negative charge), it becomes an ion and takes on a positive charge. When an atom (or molecule) gains an electron, it becomes a negative ion. An electrolyte is any substance (like salt) that becomes a conductor of electricity when dissolved in a solvent (like water).


This type of conductor is called an ‘ionic conductor’ because once the salt is in the water, it helps along the flow of electrons from one clip lead terminal to the other so that there is a continuous flow of electricity.


This experiment is an extension of the Conductivity Tester experiment, only in this case we’re using water as a holder for different substances, like sugar and salt. You can use orange juice, lemon juice, vinegar, baking powder, baking soda, spices, cornstarch, flour, oil, soap, shampoo, and anything else you have around. Don’t forget to test out plain water for your ‘control’ in the experiment!


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Nerve Tester

Saturday February 9, 2019

nerve-testerElectrical circuits are used for all kinds of applications, from blenders to hair dryers to cars. And games! Here’s a quick and easy game using the principles of conductivity.


This experiment is a test of your nerves and skill to see if you can complete the roller coaster circuit and make it from one end to the other.  You can opt to make a noisy version (more fun) or a silent version (for stealth). Are you ready?


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Latching Circuit

Saturday February 9, 2019

Once you’ve made the Pressure Sensor burglar alarm, you might be wondering how to make the alarm stay on after it has been triggered, the way the Trip Wire Sensor does.


The reason this isn’t as simple as it seems is that the trip wire is a normally closed (NC) switch while the pressure sensor is a normally open (NO) switch. This means that the trip wire is designed to allow current to flow through the tacks when there’s no paper insulating them, while the pressure sensor stops current flowing in it’s un-squished state. It’s just the nature of the two different types of switches.


However, we can build a circuit using a relay which will ‘latch on’ when activated and remain on until you reset the system (by cutting off the power). This super-cool latching circuit video will show you everything you need to know.
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Pressure Sensor Burglar Alarm

Saturday February 9, 2019

By controlling how and when a circuit is triggered, you can easily turn a simple circuit into a burglar alarm – something that alerts you when something happens. By sensing light, movement, weight, liquids, even electric fields, you can trigger LEDs to light and buzzers to sound. Your room will never be the same.


Switches control the flow of electricity through a circuit. There are different kinds of switches. NC (normally closed) switches keep the current flowing until you engage the switch. The SPST and DPDT switches are NO (normally open) switches.


The pressure sensor we’re building is small, and it requires a fair amount of pressure to activate. Pressure is force (like weight) over a given area (like a footprint). If you weighed 200 pounds, and your footprint averaged 10” long and 2” wide, you’d exert about 5 psi (pounds per square inch) per foot.


However, if you walked around on stilts indeed of feet, and the ‘footprint’ of each stilt averaged 1” on each side, you’d now exert 100 psi per foot. Why such a difference?


The secret is in the area of the footprint. In our example, your foot is about 20 square inches, but the area of each stilt was only 1 square inch. Since you haven’t changed your weight, you’re still pushing down with 200 pounds, only in the second case, you’re pressing the same weight into a much smaller spot… and hence the pressure applied to the smaller area shoots up by a factor of 20.


So how do we use pressure in this experiment? When you squeeze the foam, the light bulb lights up! It’s ideal for under a doormat or carpet rug where lots of weight will trigger it.


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Trip Wire Burglar Alarm

Saturday February 9, 2019

Burglar alarms not only protect your stuff, they put the intruder into a panic while they attempt to disarm the triggered noisemaker.  Our burglar alarms are basically switches which utilize the circuitry from Basic Circuits and clever tricks in conductivity.


A complete and exhaustive description of electronics would jump into the physics of solid state electronics, which is covered in undergraduate university courses. Instead, here is a quick description based on the fluid analogy for electric charge:


The movement of electric charge is called electric current, and is measured in amperes (A, or amps). When electric current passes through a material, it does so by electrical conduction, but there are different kinds of conduction, such as metallic conduction (where electrons flow through a conductor, like metal) and electrolysis (where charged atoms (called ions) flow through liquids).


Why does metal conduct electricity? Metals are conductors not because electricity passes through them, but because they contain electrons that can move. Think of the metal wire like a hose full of water. The water can move through the hose.  An insulator would be like a hose full of cement – no charge can move through it.


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Electric Eye

Saturday February 9, 2019

This is a super-cool and ultra-simple circuit experiment that shows you how a CdS (cadmium sulfide cell) works. A CdS cell is a special kind of resistor called a photoresistor, which is sensitive to light.


A resistor limits the amount of current (electricity) that flows through it, and since this one is light-sensitive, it will allow different amounts of current through depends on how much light it “sees”.


Photoresistors are very inexpensive light detectors, and you’ll find them in cameras, street lights, clock radios, robotics, and more. We’re going to play with one and find out how to detect light using a simple series circuit.


Materials:


  • AA battery case with batteries
  • one CdS cell
  • three alligator wires
  • LED (any color and type)
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Dimmers and Motor Speed Controllers

Saturday February 9, 2019

potSo now you know how to hook up a motor, and even wire it up to a switch so that it goes in forward and reverse. But what if you want to change speeds? This nifty electrical component will help you do just that.


Once you understand how to use this potentiometer in a circuit, you’ll be able to control the speed of your laser light show motors as well as the motors and lights on your robots. Ready?


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How to use a Digital MultiMeter

Saturday February 9, 2019

meterOne of the most useful tools a scientist can have! A digital multimeter can quickly help you discover where the trouble is in your electrical circuits and eliminate the hassle of guesswork. When you have the right tool for the job, it makes your work a lot easier (think of trying to hammer nails with your shoe).

We'll show you how to get the most out of this versatile tool that we're sure you're going to use all the way through college. This project is for advanced students.

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Wiring Up Motors

Saturday February 9, 2019

Imagine you have two magnets. Glue one magnet on an imaginary record player (or a ‘lazy susan’ turntable) and hold the other magnet in your hand. What happens when you bring your hand close to the turntable magnet and bring the north sides together?


The magnet should repel and move, and since it’s on a turntable, it will circle out of the way. Now flip your hand over so you have the south facing the turntable. Notice how the turntable magnet is attracted to yours and rotates toward your hand. Just as it reaches your hand, flip it again to reveal the north side. Now the glued turntable magnet pushes away into another circle as you flip your magnet over again to attract it back to you. Imagine if you could time this well enough to get the turntable magnet to make a complete circle over and over again… that’s how a motor works!


After you get the buzzer and the light or LED to work, try spinning a DC motor:


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Conductivity Testers

Saturday February 9, 2019

switch-zoomMake yourself a grab bag of fun things to test: copper pieces (nails or pipe pieces), zinc washers, pipe cleaners, Mylar, aluminum foil, pennies, nickels, keys, film canisters, paper clips, load stones (magnetic rock), other rocks, and just about anything else in the back of your desk drawer.


Certain materials conduct electricity better than others. Silver, for example, is one of the best electrical conductors on the planet, followed closely by copper and gold. Most scientists use gold contacts because, unlike silver and copper, gold does not tarnish (oxidize) as easily. Gold is a soft metal and wears away much more easily than others, but since most circuits are built for the short term (less than 50 years of use), the loss of material is unnoticeable.
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Basic Circuits

Saturday February 9, 2019

DSC00021An electrical circuit is like a NASCAR raceway.  The electrons (racecars) zip around the race loop (wire circuit) superfast to make stuff happen. Although you can’t see the electrons zipping around the circuit, you can see the effects: lighting up LEDs, sounding buzzers, clicking relays, etc.


There are many different electrical components that make the electrons react in different ways, such as resistors (limit current), capacitors (collect a charge), transistors (gate for electrons), relays (electricity itself activates a switch), diodes (one-way street for electrons), solenoids (electrical magnet), switches (stoplight for electrons), and more.  We’re going to use a combination diode-light-bulb (LED), buzzers, and motors in our circuits right now.


A CIRCUIT looks like a CIRCLE.  When you connect the batteries to the LED with wire and make a circle, the LED lights up.  If you break open the circle, electricity (current) doesn’t flow and the LED turns dark.


LED stands for “Light Emitting Diode”.  Diodes are one-way streets for electricity – they allow electrons to flow one way but not the other.


Remember when you scuffed along the carpet?  You gathered up an electric charge in your body.  That charge was static until you zapped someone else.  The movement of electric charge is called electric current, and is measured in amperes (A). When electric current passes through a material, it does it by electrical conduction. There are different kinds of conduction, such as metallic conduction, where electrons flow through a conductor (like metal) and electrolysis, where charged atoms (called ions) flow through liquids.


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Cosmic Ray Detector

Saturday February 9, 2019

When high energy radiation strikes the Earth from space, it’s called cosmic rays. To be accurate, a cosmic ray is not like a ray of sunshine, but rather is a super-fast particle slinging through space. Think of throwing a grain of sand at a 100 mph… and that’s what we call a ‘cosmic ray’. Build your own electroscope with this video!


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Alien Detector (Advanced)

Saturday February 9, 2019

fet1This simple FET circuit is really an electronic version of the electroscope. This “Alien Detector” is a super-sensitive static charge detector made from a few electronics parts. I originally made a few of these and placed them in soap boxes and nailed the lids shut and asked kids how they worked. (I did place a on/off switch poking through the box along with the LED so they would have ‘some’ control over the experiment.)


This detector is so sensitive that you can go around your house and find pockets of static charge… even from your own footprints! This is an advanced project for advanced students.


You will need to get:


  • 9V battery clip (and a 9V battery)
  • MPF 102  (buy 2 – one for back up)
  • LED (any regular LED works fine)
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Advanced Static Electricity Experiments

Saturday February 9, 2019

You can use the idea that like charges repel (like two electrons) and opposites attract to move stuff around, stick to walls, float, spin, and roll. Make sure you do this experiment first.


I’ve got two different videos that use positive and negative charges to make things rotate, the first of which is more of a demonstration (unless you happen to have a 50,000 Volt electrostatic generator on hand), and the second is a homemade version on a smaller scale.


Did you know that you can make a motor turn using static electricity? Here’s how:


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Seeing Electric Fields Using Your Spice Rack

Saturday February 9, 2019

Have you wrapped your mind around static electricity yet? You should understand by now how scuffing along a carpet in socks builds up electrons, which eventually jump off in a flurry known as a spark. And you also probably know a bit about magnets and how magnets have north and south poles AND a magnetic field (more on this later). Did you also know that electrical charges have an electrical field, just like magnets do?


It’s easy to visualize a magnetic field, because you’ve seen the iron filings line up from pole to pole. But did you know that you can do a similar experiment with electric fields?


Here’s what you need:


  • dried dill (spice)
  • vegetable or mineral oil
  • 2 alligator wires
  • static electricity source (watch video first!)
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Detecting the Electric Field

Saturday February 9, 2019

You are actually fairly familiar with electric fields too, but you may not know it. Have you ever rubbed your feet against the floor and then shocked your brother or sister? Have you ever zipped down a plastic slide and noticed that your hair is sticking straight up when you get to the bottom? Both phenomena are caused by electric fields and they are everywhere!


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Pinhole Camera

Saturday February 9, 2019

This is the simplest form of camera – no film, no batteries, and no moving parts that can break. The biggest problem with this camera is that the inlet hole is so tiny that it lets in such a small amount of light and makes a faint image. If you make the hole larger, you get a brighter image, but it’s much less focused. The more light rays coming through, the more they spread out the image out more and create a fuzzier picture. You’ll need to play with the size of the hole to get the best image.


While you can go crazy and take actual photos with this camera by sticking on a piece of undeveloped black and white film (use a moderately fast ASA rating), I recommend using tracing paper and a set of eyeballs to view your images. Here’s what you need to do:


Materials:


  • box
  • tracing paper
  • razor or scissors
  • tape
  • tack
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Eyeballoon

Saturday February 9, 2019

In this lab, we are going to make an eyeball model using a balloon. This experiment should give you a better idea of how your eyes work. The way your brain actually sees things is still a mystery, but using the balloon we can get a good working model of how light gets to your brain.


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Hydraulic Pneumatic Earth Mover

Saturday February 9, 2019
When people mention the word “hydraulics”, they could be talking about pumps, turbines, hydropower, erosion, or river channel flow.  The term “hydraulics” means using fluid power, and deals with machinesand devices that use liquids to move, lift, drive, and shove things around.

Liquids behave in certain ways: they are incompressible, meaning that you can’t pack the liquid into a tighter space than it already is occupying.

If you've ever filled a tube partway with water and moved it around, you've probably noticed that the water level will remain the same on either side of the tube.

However, if you add pressure to one end of the tube (by blowing into the tube), the water level will rise on the opposite side. If you decrease the pressure (by blowing across the top of one side), the water level will drop on the other side.

In physics, this is defined through Pascal's law, which tells us how the pressure applied to one surface can be transmitted to the other surface. As liquids can't be squished, whatever happens on one surface affects what occurs on the other.  Examples of this effect include siphons, water towers, and dams. Scuba divers know that as they dive 30 feet underwater, the pressure doubles. This effect is also show in hydraulics - and more importantly, in the project we're about to do!

But first, let's understand what's happening with liquids and pressure:

Here’s an example: If you fill a glass full to the brim with water, you reach a point where for every drop you add on top, one drop will fall out.  You simply can’t squish any more water molecules into the glass without losing at least the same amount. Excavators, jacks, and the brake lines in your car use hydraulics to lift huge amounts of weight, and the liquid used to transfer the force is usually oil at 10,000 psi.

Air, however, is compressible.  When car tires are inflated, the hose shoves more and more air inside the tire, increasing the pressure (amount of air molecules in the tire).  The more air you stuff into the tire, the higher the pressure rises.  When machines use air to lift, move, spin, or drill, it’s called “pneumatics”. Air tools use compressed air or pure gases for pneumatic power, usually pressurized to 80-100 psi.

Different systems require either hydraulics or pneumatics.  The advantage to using hydraulics lies in the fact that liquids are not compressible. Hydraulic systems minimize the “springy-ness” in a system because the liquid doesn’t absorb the energy being transferred, and the working fluids can handle much heavier loads than compressible gases.  However, oil is flammable, very messy, and requires electricity to power the machines, making pneumatics the best choice for smaller applications, including air tools (to absorb excessive forces without injuring the user).

We're going to build our own hydraulic-pneumatic machine.  Here's what you need to do: Please login or register to read the rest of this content.


Simple Pulley Experiments

Saturday February 9, 2019

Are you curious about pulleys? This set of experiments will give you a good taste of what pulleys are, how to thread them up, and how you can use them to lift heavy things.


We’ll also learn how to take data with our setup and set the stage for doing the ultra-cool Pulley Lift experiments.


Are you ready?
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The SeeSaw

Saturday February 9, 2019

We’re going to use everyday objects to build a simple machine and learn how to take data. Sadly, most college students have trouble with these simple steps, so we’re getting you a head start here. The most complex science experiments all have these same steps that we’re about to do… just on a grander (and more expensive) scale. We’re going to break each piece down so you can really wrap your head around each step. Are you ready to put your new ideas to the test?


This experiment is for Advanced Students.


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Human Levers

Saturday February 9, 2019

Levers are classified into three types: first class, second class, or third class. Their class is identified by the location of the load, the force moving the load, and the fulcrum. In this activity, you will learn about the types of levers and then use your body to make each type.


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Catapults

Saturday February 9, 2019

When you drop a ball, it falls 16 feet the first second you release it. If you throw the ball horizontally, it will also fall 16 feet in the first second, even though it is moving horizontally… it moves both away from you and down toward the ground. Think about a bullet shot horizontally. It travels a lot faster than you can throw (about 2,000 feet each second). But it will still fall 16 feet during that first second. Gravity pulls on all objects (like the ball and the bullet) the same way, no matter how fast they go.


What if you shoot the bullet faster and faster? Gravity will still pull it down 16 feet during the first second, but remember that the surface of the Earth is round. Can you imagine how fast we’d need to shoot the bullet so that when the bullet falls 16 feet in one second, the Earth curves away from the bullet at the same rate of 16 feet each second?


Answer: that bullet needs to travel nearly 5 miles per second. (This is also how satellites stay in orbit – going just fast enough to keep from falling inward and not too fast that they fly out of orbit.)


Catapults are a nifty way to fire things both vertically and horizontally, so you can get a better feel for how objects fly through the air. Notice when you launch how the balls always fall at the same rate – about 16 feet in the first second.  What about the energy involved?


When you fire a ball through the air, it moves both vertically and horizontally (up and out). When you toss it upwards, you store the (moving) kinetic energy as potential energy, which transfers back to kinetic when it comes whizzing back down. If you throw it only outwards, the energy is completely lost due to friction.


The higher you pitch a ball upwards, the more energy you store in it. Instead of breaking our arms trying to toss balls into the air, let’s make a simple machine that will do it for us. This catapult uses elastic kinetic energy stored in the rubber band to launch the ball skyward.


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Pendulums

Saturday February 9, 2019

This is a very simple yet powerful demonstration that shows how potential energy and kinetic energy transfer from one to the other and back again, over and over.  Once you wrap your head around this concept, you’ll be well on your way to designing world-class roller coasters.


For these experiments, find your materials:


  • some string
  • a bit of tape
  • a washer or a weight of some kind
  • set of magnets (at least 6, but more is better)
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Mystery Toy

Saturday February 9, 2019

Note: Do the pendulum experiment first, and when you’re done with the heavy nut from that activity, just use it in this experiment.


You can easily create one of these mystery toys out of an old baking powder can, a heavy rock, two paper clips, and a rubber band (at least 3″ x 1/4″).  It will keep small kids and cats busy for hours.


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Go Go GO!!

Saturday February 9, 2019

This is a nit-picky experiment that focuses on the energy transfer of rolling cars.  You’ll be placing objects and moving them about to gather information about the potential and kinetic energy.


We’ll also be taking data and recording the results as well as doing a few math calculations, so if math isn’t your thing, feel free to skip it.


Here’s what you need:


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Bobsleds

Saturday February 9, 2019

Bobsleds use the low-friction surface of ice to coast downhill at ridiculous speeds. You start at the top of a high hill (with loads of potential energy) then slide down a icy hill til you transform all that potential energy into kinetic energy.  It’s one of the most efficient ways of energy transformation on planet Earth. Ready to give it a try?


This is one of those quick-yet-highly-satisfying activities which utilizes ordinary materials and turns it into something highly unusual… for example, taking aluminum foil and marbles and making it into a racecar.


While you can make a tube out of gift wrap tubes, it’s much more fun to use clear plastic tubes (such as the ones that protect the long overhead fluorescent lights). Find the longest ones you can at your local hardware store. In a pinch, you can slit the gift wrap tubes in half lengthwise and tape either the lengths together for a longer run or side-by-side for multiple tracks for races. (Poke a skewer through the rolls horizontally to make a quick-release gate.)


Here’s what you need:


  • aluminum foil
  • marbles (at least four the same size)
  • long tube (gift wrapping tube or the clear protective tube that covers fluorescent lighting is great)
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Roller Coasters

Saturday February 9, 2019

We’re going to build monster roller coasters in your house using just a couple of simple materials. You might have heard how energy cannot be created or destroyed, but it can be transferred or transformed (if you haven’t that’s okay – you’ll pick it up while doing this activity).


Roller coasters are a prime example of energy transfer: You start at the top of a big hill at low speeds (high gravitational potential energy), then race down a slope at break-neck speed (potential transforming into kinetic) until you bottom out and enter a loop (highest kinetic energy, lowest potential energy). At the top of the loop, your speed slows (increasing your potential energy), but then you speed up again and you zoom near the bottom exit of the loop (increasing your kinetic energy), and you’re off again!


Here’s what you need:


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Special Science Teleclass: Physics of Motion

Saturday February 9, 2019

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!


We’re going to cover energy and motion by building roller coasters and catapults! Kids build a working catapult while they learn about the physics of projectile motion and storing elastic potential energy. Let’s discover the mysterious forces at work behind the thrill ride of the world’s most monstrous roller coasters, as we twist, turn, loop and corkscrew our way through g-forces, velocity, acceleration, and believe it or not, move through orbital mechanics, like satellites. We’ll also learn how to throw objects across the room in the name of science… called projectile motion. Are you ready for a fast and furious physics class?


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