(i) How the bats make use of ultrasonic waves to catch their prey ? Explain. (ii) A radar signal is reflected by an aeroplane and is received 2 x 10^-5 s after it was sent. If the speed of these waves is 3 x 108 m s^-1, how far is the aeroplane?


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(i) Bats can hear the ultrasonic waves and use these waves to navigate and detect insects in the flight. A bat sends out a wave and listens for the waves that are reflected by insect’s body.
(ii) Given, speed of radio waves = 3 x 108 m s^-1
Total time taken to reach and come back from the aeroplane = 2 x10^-5 s
Therefore, time taken to reach the aeroplane = (2 x 10^-5) / 2 = 1 x 10^-5 s
Distance of aeroplane = Speed of radio waves x time = 3 x 108 x 1 x 10^-5 = 3000 m = 3 km