PHYS2424 - Spring 2000
EXAM II - PART II
(MONDAY
VERSION)
Name : ___________________________________________
SS#: _____________________________________________
Problem 1
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(10 pts)
Problem 2
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(10 pts)
Problem 3
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(20 pts)
Problem 4
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(20 pts)
Problem 5
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(30 pts)
Problem 6
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(30 pts)
Problem 7
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(15 pts)
Problem 8
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(20 pts)
Problem 9
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(25 pts)
Problem 10
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(10 pts)
Problem 11
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(10 pts)
1.
A solenoid with 500 turns, 0.10 m long, carrying a current of 4.0 A and with a
radius of 10-2 m will have what strength magnetic field at its center? (magnetic
permeability of free space is 4x10-7 Tm/A)
2.
A proton that moves perpendicular to a magnetic field of 1.20x103 G in a
circular path of 0.08 m radius has what speed? (mp = 1.67x10-27 kg)
3.
Starting with Ampere's Law, derive the equation for the magnetic field at a given
distance r of an infinitely long current carrying wire of radius R and current Io as
shown below. (Hint: make sure that you correctly calculate the current)
Io
2
A.
r < R : Curve 1 inside the wire
1
3.
Continued
B.
r > R: Curve 2 outside the wire
4.
Staring with the integral form of Ampere-Maxwell Law derive the differential
form of the law. (Show all steps)
5.
Consider the RL circuit shown. When the switch is moved to position "A" the
current builds to 30 percent of its maximum value in 4.00 seconds.
A
R1 = 12.0 
B

R2
R1
A.
Calculate the inductance, L, of the circuit.
R2 = 5.00 
L
 = 25.0 V
5.
Continue
B.
Assume that the circuit has achieved a steady state condition (with the switch in
position A). The switch is moved to position B. Calculate the current through
resistor R2 1.00 second after the switch is moved to position B.
C.
Calculate the energy stored in the magnetic field 1.00 second after the switch is
moved to position B.
6.
A square coil of 8 turns and a side width of 10.0 cm rotates about a vertical axis in

a uniform magnetic field, B , with a constant angular speed of 2 rad/s in the
direction shown.
Direction of Rotation

B
A.
Starting with Farady's Law, find an expression for the magnitude of the emf
induced in the coil in terms of B, t, and known values.
6.
Continued
B.
The magnitude of the magnetic field is 3.13 T. Calculate the maximum magnetic
flux through the coil as it rotates.
C.
Calculate the maximum emf induced in the coil.
7.
Two current carrying wires are separated by a distance of 25.0 cm. One wire is
carrying 20.0 A and the other is carrying 10.0 A as shown below. Determine
both the direction and magnitude of the force per unit length experienced by the
20.0 A wire.
20 A
25.0 cm
15 A
8.
Use the Biot-Savart law to calculate the magnitude and direction of the magnetic
field at point P located at the center of concentric semicircles of radii a = 5.00 cm
and b = 10 cm (see figure below) when a current I = 3.00 A is maintained in the
loop.
b
a
P
9.
An RL circuit is connected to a 60 Hz house outlet as shown below.
20.0 
60 Hz
0.15 H
A.
Determine both the ratio of the voltage across the inductor to the input voltage.
B.
What is the phase angle of the current flowing through the circuit relative to the
input voltage?
10.
Compute the total inductance in the following circuit
10 h
8h
6h
4h
11.
A vector field is completely described by its flow and circulation. For each of the
following parts, write the source(s).
A.
Circulation of the Magnetic Field
B.
Flow of the Electric Field
C.
Circulation of the Electric Field
D.
Flow of the Magnetic Field