Multiple choice

Consider the following statements:

  1. In vacuum, sound travels with the maximum speed.
  2. SONAR device uses infrasonic waves to measure the distance, direction and speed of underwater objects.
  3. In dark night, bats use ultrasonic waves to search the prey.

Which of the given statements is/are incorrect?

  1. Only (1)

  2. Only (2)

  3. Only (1) & (2)

  4. Only (1) & (3)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(I) Statement (1) is wrong. Sound needs a medium to travel like air, water, steel, etc. It cannot travel through vacuum.

(II) Statement (2) is wrong. SONAR device uses ultrasonic waves to measure the distance, direction and speed of underwater objects. The frequency of ultra sonic waves is more than 20 khz (more than audible range), which are detected by some special sensors. (III) Statement (3) is correct. Bats emit ultrasonic waves, which are reflected by the prey and then detected by them.

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