20.4. Electromagnets http://www.ck12.org
The overhead portion of this machine (painted yellow) is a lifting electromagnet. It is lowered to the deck where
steel pipe is stored and it picks up a length of pipe and moves it to another machine where it is set upright and
lowered into an oil well drill hole.
Electromagnets are essential to the design of the electric generator and electric motor and are also employed in
doorbells, circuit breakers, television receivers, loudspeakers, electric dead bolts, car starters, clothes washers,
atomic particle accelerators, and electromagnetic brakes and clutches. Electromagnets are commonly used as
switches in electrical machines. A recent use for industrial electromagnets is to createmagnetic levitationsystems
for bullet trains.
Summary
- A solenoid is a long coil of wire consisting of many loops of wire that makes a complete circuit.
- An electromagnet is a piece of iron inside a solenoid.
- While the magnetic field of a solenoid may be quite large, an electromagnet has a significantly larger magnetic
field. - Electromagnets’ magnetic fields can be easily turned off by just halting the current.
Practice
Questions
http://www.youtube.com/watch?v=S6oop6RXg9w
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/65197Follow up questions:
- What components are needed to make a homemade electromagnet?
- What objects were attracted by the electromagnet in the video?