Electromagnetism | Forces at a distance | Middle school physics | Khan Academy

TL;DR

Electromagnetism is the ability of certain materials to become magnetic in the presence of an electric current, allowing for adjustable strength and changeable poles.

Transcript

• [Instructor] You know what a magnet is, but did you know that some magnets can be turned on and off? One type of temporary magnet is called an electromagnet. So what is electromagnetism? Well, the hint is in the name itself. Electro for electrical, and magnet for, well, magnet. Let's take a moment to look at the definition of what an electromagne... Read More

Key Insights

• 🎮 Electromagnets can be turned on and off by controlling the electric current, unlike permanent magnets.
• 🔁 The strength of an electromagnet can be increased by increasing the electrical current or looping the wire into a coil.
• 🏑 Changing the direction of the electric current alters the direction of the magnetic field in an electromagnet.
• ✊ Electromagnets require a power source, unlike permanent magnets.
• 😷 Electromagnets find applications in motors, speakers, and medical scanners.
• 🏑 Electromagnetic fields generated by spinning magnets are utilized to generate electricity.
• 🏑 Electromagnetism is an essential force and has significant implications in various fields.

Questions & Answers

Q: What are electromagnets and how do they work?

Electromagnets are temporary magnets that become magnetic in the presence of electricity. Electrically-charged particles in motion create magnetic fields around them, which are intensified when electricity runs through a wire, resulting in an electromagnet.

Q: How can the strength of an electromagnet be increased?

The strength of an electromagnet can be increased by increasing the electrical current flowing through the wire. This is achieved by moving more electric charges through the wire at a faster rate.

Q: How can the direction of the magnetic field in an electromagnet be changed?

The direction of the magnetic field in an electromagnet can be changed by changing the direction of the electricity running through the wire. This alters the orientation of the magnetic fields and consequently, the poles of the electromagnet.

Q: How are electromagnets different from permanent magnets?

Electromagnets differ from permanent magnets as they require a power source to generate the electricity necessary to produce magnetic fields. Additionally, the strength and direction of electromagnets can be adjusted, whereas permanent magnets have fixed poles and strength.

Summary & Key Takeaways

• Electromagnets are temporary magnets that can be turned on and off using electricity.

• Electrically-charged particles in motion create magnetic fields around them, resulting in a magnetic field when electricity runs through a wire.

• The strength and direction of the magnetic field in electromagnets can be controlled by increasing the electrical current or looping the wire into a coil.