Unit 4: Electricity and Magnetism
Circuits that light up the moment a loop closes, magnets that pull without touching, and the currents tying the two together.
6 topics · 24 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Static Electricity
- How it worksHow does rubbing two materials together strip electrons from one and pile them onto the other?
- Common mistakeWhy doesn't static electricity create brand new electric charge instead of just moving charges that were already there?
- Common mistakeWhy doesn't static electricity build up as easily on a humid, rainy day as it does on a dry winter day?
- Going furtherWhat happens to a stream of water when you bring a charged balloon close to it?
- Ties togetherHow does static electricity building up inside storm clouds connect to why lightning strikes happen?
Your turn1 of 2
Rubbing a balloon on your hair makes it able to stick to a wall. Does rubbing CREATE brand new electric charge that wasn't there before?Circuits: Completing the Loop
- How it worksHow does electricity flow in one unbroken loop from the battery, through the bulb, and back again?
- How it worksWalk me through the difference between a series circuit and a parallel circuit with two light bulbs.
- Worked exampleFind how many bulbs stay lit if one bulb burns out in a series circuit of 4 bulbs, versus a parallel circuit of 4 bulbs.
- Common mistakeWhy doesn't electricity get used up and disappear as it flows around a circuit?
- Going furtherWhat happens to the brightness of two bulbs when you add a third bulb into the same series circuit?
Your turn1 of 2
Find how many bulbs stay lit if one bulb burns out in a PARALLEL circuit of 8 bulbs (each bulb has its own separate loop back to the battery).Electrical Conductors and Insulators
- How it worksHow do the loose electrons in a metal let electric current flow easily through a conductor?
- Common mistakeWhy doesn't every metal conduct electricity exactly the same amount?
- Ties togetherHow does wrapping a wire's metal conductor in a plastic insulator connect to why cords don't shock you when you hold them?
Your turn1 of 2
Why is the metal fork in your kitchen drawer always paired with plastic or rubber handles on other tools?Magnets and Magnetic Fields
- How it worksHow does a magnet's invisible field pull on certain metals and push or pull on other magnets?
- How it worksWalk me through why iron filings sprinkled near a magnet line up in curved paths between the poles.
- Common mistakeWhy doesn't a magnet attract every single metal object, like aluminum foil or a copper penny?
- Going furtherWhat happens to two magnets' pull when you flip one of them so the same poles face each other?
Your turn1 of 2
Can a magnet pull a paperclip toward it without ever physically touching it?Electromagnets
- How it worksHow does coiling a wire around an iron nail and running current through it create a magnetic field on demand?
- Worked exampleFind what happens to an electromagnet's strength if you double the number of coils of wire wrapped around the nail.
- Common mistakeWhy isn't an electromagnet just a regular magnet that happens to have wire wrapped around it?
Your turn1 of 2
An electromagnet's strength is roughly proportional to its number of coils. If a 73-coil electromagnet lifts a certain weight, find how many coils are needed to roughly double its strength.Renewable and Nonrenewable Energy
- How it worksHow does a wind turbine or solar panel keep making electricity without ever running out of fuel?
- Common mistakeWhy isn't renewable the same thing as never causing any environmental impact at all?
- Going furtherWhat happens to a solar panel's electricity output on a cloudy day compared to a sunny one?
- Ties togetherHow does burning fossil fuels for energy connect to the carbon that builds up in the atmosphere?
Your turn1 of 2
Why will the coal and oil we burn for energy today never come back, no matter how long we wait?