Download Quiz3 - 203 .tst

Physic 203 - Spring 2006 - Quiz3
04/18/06 Quiz is due to Tue
Name:
04/25/06
ID:
NOTE: cross answer e) when none of the given answers are correct
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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 25-2
1) For an xyz coordinate system shown in Figure 25-2, if the E-vector is in the +z direction, and the B-vector is in
the +x direction, what is the direction of propagation of the electromagnetic waves?
A) +z
B) -x
C) +x
D) +y
Answer: D
2) Electromagnetic waves can be produced by
A) electric charges in accelerated motion.
B) electric charges moving with constant velocity.
C) electric charges at rest.
D) All of the previous answers are correct.
Answer: A
3) In Fizeau's experiment to measure the speed of light, the wheel has 475 notches and rotates with a speed of 40.0
rev/sec. Light passing through one notch travels to the mirror and back just in time to pass through the next
notch. If the distance between the wheel and the mirror is 7890 m, what is the speed of light measured by this
experiment?
A) 3.00 ˛ 10-8 m/s
B) 3.22 ˛ 108 m/s
C) 3.00 ˛ 108 cm/s
D) 3.00 ˛ 108 m/s
Answer: D
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4) A car is approaching a radio station at a speed of 30.0 m/s. If the radio station broadcasts at a frequency of 74.5
MHz, what change in frequency does the driver observe?
A) 7.46 Hz
B) 726 Hz
C) 98.3 Hz
D) 64.5 Hz
Answer: A
5) The value of the magnetic field for a certain type of electromagnetic wave is 1.82 mT. What is the value of the
electric field for that wave?
A) 546 V/m
B) 546 J/Cm
C) 546 N/C
D) All of the answers given are correct.
Answer: D
6) A 60.0 W light bulb radiates light uniformly in all different directions. What is the value of E at a distance of
0.400 m from the bulb?
A) 52.9 N/C
B) 106 N/C
C) 162 N/C
D) 82.1 N/C
Answer: B
7) An 8.000-mW laser beam emits a cylindrical beam of light 0.9000 mm in diameter. What is the rms value of the
electric field in this beam?
A) 2000 N/C
B) 4122 N/C
C) 2176 N/C
D) 1088 N/C
Answer: C
8) The magnetic energy density of an electromagnetic wave is 8.95 ˛ 10-5 J/m 3 . What is the magnetic field
component of this wave?
A) 15.0 mT
B) 14.0 mT
C) 12.0 mT
D) 13.0 mT
Answer: A
9) The energy density of an electromagnetic wave is
A) entirely in the magnetic field.
B) entirely in the electric field.
C) equally divided between the magnetic and the electric fields.
D) zero.
Answer: C
10) If the magnetic field in a traveling electromagnetic wave has a maximum value of 16.5 nT, what is the
maximum value of the electric field associated with it?
A) 4.95 ˛ 10-1 V/m
B) 55.0 ˛ 10-16 V/m
C) 49.5 ˛ 10-1 V/m
D) 5.5 ˛ 10-17 V/m
Answer: C
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Figure 25-3
11) Figure 25-3 shows three polarizing disks having parallel planes with the direction of the transmission axis in
each case. The disks are centered on a common axis. If a plane polarized beam of light is incident from left on
the first disk with an intensity of 40 W/m 2 . What is the transmitted intensity coming out of the third disk,
when q1 = 10e, q2 = 40e, q3 = 70e?
A) 18 W/m 2
B) 0 W/m 2
C) 40 W/m 2
Answer: D
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D) 22 W/m 2