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# exam2v2ans - 0002-1 Exam II Physics 1240 – Spring 2010...

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Unformatted text preview: 0002-1 Exam II - Physics 1240 – Spring, 2010 – version 2 1. A light bulb has a power of 60 J/s (also called 60 Watts). After being on for 5 seconds how much energy has the bulb released? A) 600 J B) 300 J C) 200 J D) 100 J E) 60 J 2. A speaker in the stadium is emitting a loud, steady sound which spreads out and reaches you. You have two “receiver microphones” to pick up the sound. Microphone #2 is bigger, it has twice the receiving area as microphone #1. Both microphones listen to the same sound at the same spot for the same amount of time. Consider the following two statements and decide if each is true or false: i) The energy absorbed by microphone #2 is twice the energy absorbed by microphone #1. ii) The intensity of sound at the location of each microphone is the same. A) Statement i is true , but ii is false . B) Statement i is false , but ii is true . C) Both i and ii are true . D) Both i and ii are false . 3. I play a pure tone of frequency 100 Hz, which reflects off the wall I am facing. The bumps and irregularities on the wall are about 30 cm wide (or smaller). What will happen and why? A) The sound will largely reflect specularly because the surface is rough . B) The sound will largely reflect specularly because the surface is smooth . C) The sound will largely reflect specularly , it doesn’t matter whether the surface is smooth or rough. D) The sound will largely reflect diffusely because the surface is rough . E) The sound will largely reflect diffusely because the surface is smooth . 4. How will the sound of a wind instrument change if you alter it (e.g., by sliding a pipe, or closing holes) in such a way that the tube gets longer by a factor of 4? A) The pitch goes up by 1 octave. B) The pitch goes up by 2 octaves. C) The pitch goes down by 1 octave. D) The pitch goes down by 2 octaves. E) The pitch stays pretty much the same, tube length does not play a big role in determining pitch of a wind instrument. 5. What happens, in the previous question, if instead you swap instruments for one of the same length, but with 2 times wider tube diameter? (See the figure.) A) The pitch goes up by 1 octave. B) The pitch goes up by 2 octaves. C) The pitch goes down by 1 octave. D) The pitch goes down by 2 octaves. E) The pitch stays pretty much the same, tube diameter does not play a big role in determining pitch of a wind instrument. Length Diameter 0002-2 6. A sound intensity level (SIL) of 80 dB corresponds to what sound intensity, in W/m 2 ? A) 10 4 W/m 2 B) 10-2 W/m 2 C) 10-4 W/m 2 D) 10-6 W/m 2 E) 10-8 W/m 2 7. What is the frequency of the note which is three octaves above 100 Hz? A) 800 Hz B) 600 Hz C) 400 Hz D) 200 Hz E) 103 Hz 8. Suppose you pluck a guitar string and listen to the sound produced, then put your finger down halfway along the string and pluck it again. What happens to the sound produced?...
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exam2v2ans - 0002-1 Exam II Physics 1240 – Spring 2010...

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