Please Answer ALL. Thanks. Sound waves emanating from a speaker are directed alo

Question

Please Answer ALL.

Thanks.

Sound waves emanating from a speaker are directed along two separate parallel lengths of tubing, with one of the tubes having an adjustable slide. The sound waves have a frequency of 2300 Hz on a day when the speed of sound is 345 m/s. The tubes meet and the waves recombine at the far ends of the tubes. The waves will interfere destructively if one tube is longer than the other by a. 15 cm. b. 30 cm. c. 45 cm. d. 60 cm. e. 67.5 cm. A student wants to establish a standing wave on a wire 1.8 m long clamped at both ends. The wave speed is 540 m/s. What is the minimum frequency in Hz she should apply to set up standing waves? a. 150 b. 50 c. 100 d. 125 e. 175 The wavelength of light visible to the human eye is of the order of 5 times 10^-7 m. If the speed of light in air is 3 times 10^8 m/s, find the frequency of the light wave in Hz. a. 2 times 10^7 b. 4 times 10^9 c. 5 times 10^11 d. 6 times 10^14 e. 4 times 10^15

Explanation / Answer

condition for constructive interference is

path difference =n lamda

=n v/f

= 1( 345)/2300 Hz)

= 0.15 m

= 15 cm

for distruve interference path difference is lamda/2 = 15 cm/2 = 7.5 cm

first four options are integral muliple of constructive interference

1(15) = 15 cm

2(15) = 30 cm

( 3(15) = 45 cm

4 ( 15cm) = 60 cm

but last option gives disrucive intereference

60 cm + 7.5 cm = 67.5 cm

so length of one tube 67.5 cm more than other

option (e) is correct answer

(b)

f = v/2L = 540/ 2( 1.8)

=150 Hz

(c)

f= c/lamda = 3 * 10^8/5* 10^-7 = 6* 10^14 Hz

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