Question 29: Waves

Question

A bat emitting an ultrasonic wave of frequency 4.5 $$	imes$$ 10
4
Hz at speed of 6 m/s between two parallel walls. The two frequencies heard by the bat will be

Accepted Answer

Frequency received by bat after reflection from wall-1,
$${f_1} = f\left[ {{{v + u} \over {v - u}}} ight] = 4.5 	imes {10^4}\left[ {{{330 + 6} \over {330 - 6}}} ight]$$
Given, $$f = 4.5 	imes {10^4}$$ Hz
$$ \Rightarrow {f_1} = 4.67 	imes {10^4}$$ Hz
Frequency received by bat after reflection from wall-2,
$${f_2} = f\left[ {{{v - u} \over {v + u}}} ight]$$
$$ = 4.5 	imes {10^4}\left[ {{{330 - 6} \over {300 + 6}}} ight]$$
$$ = 4.34 	imes {10^4}$$ Hz

Answer

4.67 $$	imes$$ 10
4
Hz, 4.34 $$	imes$$ 10
4
Hz

Answer

4.34 $$	imes$$ 10
4
Hz, 4.67 $$	imes$$ 10
4
Hz

Answer

4.5 $$	imes$$ 10
4
Hz, 5.4 $$	imes$$ 10
4
Hz

Answer

4.67 $$	imes$$ 10
3
Hz, 4.34 $$	imes$$ 10
3
Hz

Waves

A bat emitting an ultrasonic wave of frequency 4.5 $\times$ 10 4 Hz at speed of 6 m/s between two parallel walls. The two frequencies heard by the bat will be

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