Suppose both frequencies are changed to frequency f. The listener moves to point
ID: 1540463 • Letter: S
Question
Suppose both frequencies are changed to frequency f. The listener moves to point Q and finds that he can hardly hear the sound, indicating destructive interference. Let f = 250 Hz and D is not given. How much further is point Q from S_2 than it is from S_1? 0.715 m, 0.746 m, 0.665 m, 0.686 m The listener returns to point P and speaker 2 is turned off. Speaker 1 broadcasts power P isotropically. What is the sound intensity (in w/m^2) that the listener hears? Let P = 300 W. 2.76 times 10^-4 3.82 times 10^-4 4.71 times 10^-4 5.46 times 10^-4 How many decibels does this sound level have if the threshold of hearing is 10^-12 W/m^2 85.8 dB, 86, 7 dB, 87.4 dB, 84.4 dB A candle of height w is located a distance D from a concave spherical mirror of radius R. Let w = 0.025 m, D = 4.20 m and R = 1.60 m. What is the focal length of the mirror? 0.85m, 0.90 m, 0.75 m, 0. 80 m How far from the mirror will the image be? 0.988 m, 1.054 m, 1.119 m, 0.923 m How tall will the image be? 0.0085 m, 0.0046 m, 0.0059m, 0.0072 m The image will be Real and upright Real and inverted Virtual and upright virtual and inverted.Explanation / Answer
13) Given Power = P = 3.0 W
Consider Radius = R = 45 m (Not given here)
Area = A = pi*R^2 = 6361.725 m^2
Sound intensity = I = P/A = 3/6361.725 = 4.71*10^-4 W/m^2