Learning Objectives
After studying this chapter, you will be able
to do the following:
• Demonstrate how to induce a voltage
using a coil and a magnet.
• Explain four things that affect the
amount of inductance in a coil.
• Draw the symbols for a fi xed and
adjustable inductor.
• Calculate the power and current on the
secondary of a transformer.
211
Electromagnetic
Induction
12 1 2
Technical Terms
closed-form transformer
counter-electromotive force
henry (H)
induced emf
inductance
inductor
magnetic coupling
mutual inductance
primary
secondary
shell-form transformer
step-down transformer
step-up transformer
tap
total inductance
transformers
volt-ampere
In Chapter 10, you learned that a magnetic
fi eld is created around a conductor when
current fl ows through it. You also learned that
moving a magnetic fi eld across a conductor
or moving a conductor across a magnetic
fi eld creates current in the conductor. Both of
these occur in a circuit that contains a coil, or
an inductor. This chapter takes a closer look