passwella.
Menu

JAMB Physics 1990 Question 22

Question 22

Waves

A wave disturbance travelling in air enters a medium in which its velocity is less than that in air. Which of the following statements is true about the wave in the medium?

  1. A.Both the frequency of the wave and the wavelength are decreased
  2. B.The frequency of the wave is decreased while the wavelength is increased
  3. C.The frequency of the wave is unaltered while the wavelength is decreased.
  4. D.The frequency of the wave is decreased while the wavelength is unaltered.
Show the answer and explanation

Answer: C (The frequency of the wave is unaltered while the wavelength is decreased.)

Explanation

The frequency is fixed by the source. With a lower speed, λ = v/f becomes shorter.