Guitar Amplifier Microphone Quiz

A microphone of cross-sectional area \frac {\pi}{4}cm2 is placed in front of a guitar amp./speaker emitting 16 W of sound output. If the distance between the microphone and the speaker is 2.0 cm, the energy falling on the microphone in 4.0 s is:

(A) 1 J
(B) 1 mJ
(C) 4 J
(D) 0.25 J

 

Sound Reflection Quiz

During music practice session, students sing SA-PA SA-PA on mic. The sound is reflected back from a building at a distance of 85 m from the class. Which one of the following is the time interval between one SA-PA and the next SA-PA so that the reflected sound synchonises exactly with the emitted sound? Speed of sound in air is 340 m/s.

(A) 0.5 s
(B) 0.25 s
(C) 1 s
(D) 0.025 s

Solution

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