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Course: Middle school physics>Unit 2

Lesson 7: Electromagnetism

Electromagnetism

Moving electric charges create magnetic fields in the space around them. These magnetic fields can be used to generate magnetic forces. Oppositely, when magnetic fields are changed around charges, they can create moving electric charges, or electricity. Both of these phenomena are called electromagnetism, which is used in everyday items, from motors to medical scanners. Created by Khan Academy.

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Moving electric charges create magnetic fields in the space around them. We can use these magnetic fields to generate magnetic forces. Oppositely, when we change magnetic fields around charges we can create moving electric charges, or electricity. We call both of these phenomena electromagnetism. Incredibly useful, there are devices in everyday life that use electromagnets and electromagnetism.
• How can a magnetic field have direction? Are there particles around a magnet that move in one direction or other?
• A magnetic field can have direction because the particles that surround it are either moving in the north or south direction
• What would happen if you put permanent magnet close to a electric magnet, would the electric current change directions.
• If you put a permanent magnet close to an electromagnet, it can indeed affect the direction of the electric current flowing through the electromagnet
• How do you know the direction of a magnetic field?
• The direction of the magnetic field around a coil can be determined by using the right-hand rule. Place your right hand around the coil with your thumb pointing in the direction of the current flow, your fingers will curl in the direction of the magnetic field.
• What if you charge a permanent magnet?
• charging a permanent magnet won't change its magnetic properties. It will remain a magnet and keep its magnetic field intact, regardless of any electric charge you give it.
• What determines the strength of a permanent magnet?
• A magnet's strength is affected by its size and the material it is made of. The environment also affects it (e.g. surrounding temperature).
• How does a spinning magnet cause an electric current? Not sure I fully understand the mechanics
• When a magnet spins near a wire, it creates a changing magnetic field. This changing field induces an electric current in the wire through electromagnetic induction.
• Does this mean that everything that has electricity in it is also a magnet? My toothbrush?