In a circuit made up of inductor L, resistor R, ammeter, battery, and switch in series, the current is greatest at which of the following times, as measured after the switch is closed?
a. ten time constants
c. one time constant
b. at a time t = L/R
d. zero
[Ques. 2] Waves propagate at 4.0 m/s along a stretched string. The end of the string is vibrated up and down once every 3.0 s. What is the wavelength of the waves that travel along the string?
a. 3.0 m
c. 6.0 m
b. 12 m
d. 2.7 m
[Ques. 3] One time constant after an RL circuit has its switch closed, how does the current I in it compare to the maximum current Imax that occurs for this circuit?
a. I > Imax/2
b. I = Imax/2
c. I < Imax/2
d. Without knowing R and L, this cannot be determined.
[Ques. 4] Bats can detect small objects such as insects that are of a size approximately that of one wavelength. If bats emit a chirp at a frequency of 50 kHz, and the speed of sound waves in air is 330 m/s, what is the smallest size insect they can detect?
a. 1.5 mm
c. 5.5 mm
b. 3.7 mm
d. 6.6 mm
[Ques. 5] Two solenoids, wound from wire from the same spool, have the same length and cross-sectional area, but solenoid 1 has twice the turns of solenoid 2 . If these solenoids are each connected to a circuit, and the only non-negligible resistance is that of the solenoids, which solenoid gives the greater time constant and by what factor?
a. 2 by a factor of 2
c. 1 by a factor of 2
b. 2 by a factor of 4
d. No answer above is completely correct.
[Ques. 6] Consider the curve f(x) = A cos(2px/l). The wavelength of the wave will be:
a. the distance 0 to A.
c. twice the distance x2 to x3.
b. twice the distance 0 to A.
d. the distance x2 to x3.
[Ques. 7] Which of the following is referred to as mutual inductance?
a. Two unconnected inductors have their coils wound in the same pattern.
b. Two solenoids have the same inductance.
c. The changing flux from one inductor produces an emf in another inductor.
d. The numerical value of one inductance is the reciprocal of another inductance in the same circuit.
[Ques. 8] If a radio wave has speed 3.00 108 m/s and frequency 99.7 MHz, what is its wavelength?
a. 8.78 m
c. 2.78 m
b. 1.50 m
d. 3.01 m
[Ques. 9] The first solenoid has 2 times the diameter, 2 times the number of turns, and 2 times the length of the second solenoid. Which solenoid has the greater inductance and by what factor?
a. the first solenoid by a factor of 8
c. the first solenoid by a factor of 16
b. the second solenoid by a factor of 8
d. the second solenoid by a factor of 32
[Ques. 10] A musical tone, sounded on a piano, has a frequency of 820 Hz and a wavelength in air of 0.400 m. What is the wave speed?
a. 587 m/s
c. 235 m/s
b. 328 m/s
d. 170 m/s
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