Manage this Assignment:
7. Induction Part 2
Due: 11:00pm on Thursday, February 25, 2010
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Energy Stored in an Inductor
Description:
Numerical calculation of the inductance necessary to store a given amount of energy.
The electric-power industry is interested in finding a way to store electric energy during times of low demand for use
during peak-demand times. One way of achieving this goal is to use large inductors.
Part A
What inductance
would be needed to store energy
(kilowatt-hours) in a coil carrying current
?
This is probably not the best way to store energy: unless the coil is a superconductor, the amount of heat
dissipated in the coil would be enormous. At this point, there is no way to produce large superconducting
coils. Think of this problem as a practice exercise rather than a realistic example.
Hint A.1
The formula for the energy stored in a current-carrying inductor
Recall the formula for energy stored in an inductor:
.
Hint A.2
Express the energy in joules
What is the energy
expressed in joules?
Express your answer numerically, to three significant figures.
ANSWER:
=
joules
ANSWER:
=
H
RL Circuit Phasor Drawings Applet Vector
Description:
For an RL circuit, given the current phasor, draw the resistor, inductor, and total voltage phasors.
(vector applet)
An RL circuit is driven by an AC voltage source as shown in the figure.
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