If the air temperature decreases, how does the resonant frequency in a pipe closed at one end change?
a. It increases.
b. It decreases.
c. It doesn't change since one end of the pipe is closed.
d. It doesn't change because resonance is pressure phenomenon.
[Ques. 2] 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. 3] The air in a tube open at both ends is sent into its fundamental resonance. One end of the tube is then closed and the air column is again set into its fundamental resonance. The resonant frequency ____ after the end is closed.
a. halves
b. stays the same
c. doubles
d. increases by a factor of 1.4
[Ques. 4] An air-core inductor has 920 turns/m and an internal volume of 3.0 cm3 . What is its inductance?
a. 3.2 H
b. 2.8 mH
c. 0.35 H
d. 32 H
e. Insufficient information is given.
[Ques. 5] A flute behaves like a tube open at both ends. If its length is 67.0 cm, and the speed of sound is 340 m/s, what is its fundamental frequency in Hz?
a. 127 Hz
b. 168 Hz
c. 670 Hz
d. 254 Hz
e. 507 Hz
[Ques. 6] The unit of inductance, the henry, is equivalent to
a. Vs/A.
b. V/m.
c. J/C.
d. none of the units given.
[Ques. 7] If two adjacent frequencies of an organ pipe closed at one end are 385 Hz and 578 Hz, what is the length of the organ pipe? (vsound = 340 m/s)
a. 0.44 m
b. 0.59 m
c. 1.4 m
d. 0.88 m
e. 1.8 m
[Ques. 8] The magnetic field going through a stationary circular loop increases from zero to 5 T in a certain time t. The induced current in the loop will depend on the radius of the loop, r, the resistance of the loop, R, and the time, t. If two of these stay constant, the induced current can be directly proportional to
a. t.
b. r.
c. R.
d. none of these
[Ques. 9] For a standing wave in an air column in a pipe that is open at both ends, there must be at least
a. one node and one antinode.
b. two nodes and one antinode.
c. two antinodes and one node.
d. two nodes and two antinodes.
[Ques. 10] Two loops of wire are arranged so that a changing current in one, the primary, will induce a current in the other, the secondary. The secondary loop has twice as many turns as the primary loop. The current in the primary at this moment is 3 A and increasing. The current in the secondary must be
a. 3 A.
b. 6 A.
c. zero.
d. There is insufficient information to work this problem.
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