Ch. 3 Sec. 1What is electromagnetism?

electromagnetism

relationship between electricity & magnetism

electric current produces magnetic field

Magnetic Field Map Iron filings show the magnetic field lines around a wire with a current. What is the shape of the field lines?

solenoid

coil of wire w/ currentstrength of magnetic field increases

as # of loops (coils) increase

The magnetic field around a solenoid resembles that of a bar magnet.

electromagnet

solenoid w/ ferromagnetic core

strong magnet that can be turned on & off

Electromagnets [02:16]

ways to increase strength of electromagnets

1. Increase current

2. Add more loops of wire

3. Wind coils closer together

4. Use stronger ferromagnetic

material for coreOnline Interactive Activity-Make an electromagnet

electromagnets at work

doorbelljunkyard

crane

Roller coasters uses electromagnets to launch and stop the roller coaster.

Olivia's Challenge: Build Your Own Electromagnet [00:24]

Make an electromagnet

1. How many paper clips will your electromagnet hold?

2. Can you hang paper clips on both ends of the nail?

3. How can you make your electromagnet stronger?

4. After using the electromagnet, remove the iron nail. Can the nail still pick things up? If so, why?

Additional experiments to try:

1. Change the shape of the armature (coil of wire)

2. Hold the magnet above the coil.

# of coils # of paper clips picked up

Coils close together or far apartAmount of current

Electromagnet experiment