Seventh Grade Physics of Light

Getting Started

Scientist are still trying to make heads or tails of this thing called light, and near as they can tell, it sometimes interacts like a particle (like a marble) and other times like a wave (like on the ocean), and you really can’t separate the two because they actually complement each other.

Energy can take one of two forms: matter and light (called electromagnetic radiation). Light is energy in the form of either a particle or a wave that can travel through space and some kinds of matter, like glass.

We’re going to investigate the wild world of the photon that has baffled scientists for over a century. Low electromagnetic radiation (called radio waves) can have wavelengths longer than a football field, while high-energy gamma rays can destroy living tissue.

Here are the scientific concepts:

• Light is energy that can travel through space.
• Light you can see (visible light like a rainbow) makes up only a tiny bit of the entire electromagnetic spectrum.
• Light has wavelength (frequency, or color), intensity (brightness), polarization (direction), and phase (time shift).
• Visible light is a small band within a very broad electromagnetic spectrum.
• White light is a mixture of many wavelengths (colors), and that retinal cells react differently with different wavelengths.
• For an object to be seen, light emitted by or scattered from it must enter the eye.
• When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object’s material and the frequency (color) of the light.
• Light travels in straight lines except when the medium it travels through changes.
• Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection).
• The angle of reflection of a light beam is equal to the angle of incidence.
• The path that light travels can be traced as straight lines, except at surfaces between different transparent materials (e.g., air and water, air and glass) where the light path bends.
• A simple wave has a repeating pattern with a specific wavelength, frequency, and amplitude.
• How simple lenses are used in a magnifying glass, the eye, camera, telescope, and microscope.

By the end of the labs, students will be able to:

• Design and build both a refractor and reflector telescope using lenses.
• Show and describe a mathematical model for waves that shows how amplitude is related to the energy of a wave.
• Develop an experiment that shows how waves are reflected, absorbed, and transmitted.
• Know how to demonstrate how compound microscopes work.
• Understand how to determine how to measure the speed of light.
• Differentiate observation from inference (interpretation) and know scientists’ explanations come partly from what they observe and partly from how they interpret their observations.
• Measure and estimate the weight, length and volume of objects.
• Formulate and justify predictions based on cause-and-effect relationships.
• Conduct multiple trials to test a prediction and draw conclusions about the relationships between predictions and results.
• Construct and interpret graphs from measurements.
• Follow a set of written instructions for a scientific investigation.