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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What if you have iron ore and smelt it so it is 100% iron and you shape it into a torch and you put a light bulb onto it, will it be on as long as you shake it?