Unformatted text preview: nds only on the amplitude of the
generator emf, not on its frequency.
Version 1 Page 10 18. In the circuit below the three resistors are the same at 10 Ω each and the inductor has L =
35 mH. What is the potential difference across the inductor immediately after closing
the switch? We do know that the current through the battery is 4.0 A after the switch has
been closed for a very long time. L
E) Two options.
1) calculate the 19.
B field of the
wire in the
multiply by 18.
This is NOT an
exact answer (it
B by about
20%) but it is
close enough to
answer to allow
you to choose it.
2) integrate the
gives a very
but is more
option 1. 10
0 In the instant after the switch is closed the current
through the inductor is zero. All current goes
through loop 1 only. The voltage across the
inductor must be the same as the voltage across
the second resistor in loop 1. Since the two
resistors in loop 1 are identical the voltage across
each must be half the battery voltage. That
means the inductor also has half of the battery
voltage across it, so V_L=30 volts. Eighteen very long, straight conductors with square cross sections carrying current of 5 A
straight out of the page are laid side by side to form a current sheet as shown in the
diagram. What is the magnitude and direction of the magnetic field at point P, 0.03 m
from one edge of the sheet as shown? P 0.03 m 0.12 m
E) -4 2.8 x 10 T,
1.5 x 10-5 T,
6.9 x 10-5 T,
9.5 x 10-7 T,
3.2 x 10-6 T, down
down Version 1 Page 11 20. An LC circuit is composed of an ideal solenoid and a capacitor (no resistance in the
circuit). It oscillates at some natural frequency f0. If we now fill the volume of the
solenoid with a ferromagnetic material that has permeability Km = 3000 what happens to
the natural frequency?
A) it is 55 times higher
B) it is 3000 times higher
C) it is unchanged
D) it is 3000 times lower
E) it is 55 times lower Version 1 Page 12 Answer Key
E Version 1 Page 13...
View Full Document
- Fall '08
- Physics, Magnetic Field