25.2. Using Electromagnetism http://www.ck12.org
25.2 Using Electromagnetism
Lesson Objectives
- State how a solenoid increases electromagnetic force.
- Explain why electromagnets can be very strong.
- Describe how doorbells and electric motors use electromagnetism.
Lesson Vocabulary
- electric motor
- electromagnet
- solenoid
Introduction
Do you believe in ghosts? The man in theFigure25.4 does. He’s hoping to record sights or sounds of ghost on his
video camera. The other device he’s holding is an electromagnetic field detector. Ghost hunters often use detectors
like this one because they believe that ghosts cause changes in electromagnetic fields. The problem for ghost hunters
is that electromagnetic fields can be produced by many devices. You can read about some of them in this lesson.
They may not be as exciting as ghosts, but they are a lot more useful!
FIGURE 25.4
This man is trying to detect “evidence” of
a ghost.