Page 15 - Electrical Equipment Handbook _ Troubleshooting and Maintenance

FUNDAMENTALS OF ELECTRIC SYSTEMS

1.14 CHAPTER ONE

FIGURE 1.17 In practice the sharp corners would be rounded.

From Faraday’s law, we can write the induced voltage (emf) as
d(N
B ) di
L
dt dt
This relationship can be used for inductors of all shapes and sizes. In an inductor (symbol
), L depends only on the geometry of the device. The unit of inductance is the henry
(abbreviated H). It is given by

1 volt
second V
s
1 henry (H)
ampere A
In an inductor, energy is stored in a magnetic field. The amount of magnetic energy stored
U in the inductor is given by
B
U ⁄2 Li 2
1
B
In summary, an inductor stores energy in a magnetic field, and the capacitor stores energy
in an electric field.

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