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Old-Examination-Questions-Ch.#17 (Dr. Gondal -Phys102)
T081
Q5.A pipe has two consecutive resonance frequencies of 600 Hz and 1000 Hz. One end of the pipe is closed. What is the fundamental frequency of the pipe? (Ans: 200 Hz)
Q6.The intensity of sound emitted by a source is doubled. What is the change in intensity level of the sound? (Ans: 3.0 dB)
Q7.Two identical loudspeakers, facing each other, are in phase and each has a frequency of 85 Hz. A man at the midpoint between the two loudspeakers moves slowly toward one of them until he hears the first minimum in sound. How far did he move? (The speed of sound in air = 340 m/s) (Ans: 1.0 m)
Q8.If it were possible for a man to move with the speed of sound directly toward a stationary whistle emitting a sound of frequency f, he would hear (Ans: a sound of frequency 2f)
T072
Q6.
Two speakers S1 and S2 are placed on the y-axis as shown in figure 1. The speakers are in phase and emit identical sound waves with a given frequency. An observer, standing at point A, hears a sound of maximum intensity. As the observer moves along a straight line parallel to the y-axis and reaches point B, he hears first minimum of sound intensity. The frequency of sound emitted by the speakers is? (speed of sound in air = 343 m/s). (Ans: 121 Hz)
Q7. A stationary train passenger hears a frequency of 520 Hz as a train approaches a bell on a trackside safety gate. After the train passes the gate the passenger hears a frequency of 480 Hz for the bell sound. The speed of the train is : ( speed of sound in air = 343 m/s) (Ans: 13.7 m/s)
Q8: The intensity of a certain sound wave is 6 mW/cm2. If its sound level is raised by 10 decibels, the new intensity (in mW/cm2) is: (Ans: 60)
Q9. If the speed of sound is 340 m/s, the two lowest resonance frequencies of a 0.5 m organ pipe, closed at one end, are approximately: (Ans: 170 and 510 Hz)
T071
Q#5. In the figure below, two speakers are driven by the same generator and are a distance of 1.0