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JAMB Physics 1983 Question 11

Question 11

Sound

Which of the following is NOT correct? I. The pitch of a sound note depends on the frequency of vibrations. II. The intensity of a sound note is proportional to the amplitude of vibrations. III. Beats are produced by two sources of sound because one wave is travelling faster than the other. IV. When two sources of sound of frequencies 500 Hz and 502 Hz are sounded together, a beat frequency of 2 Hz is observed. V. The first harmonic of a note has double the frequency of the fundamental note.

  1. A.I and II
  2. B.II and III
  3. C.I and III
  4. D.III and IV
  5. E.IV and V.
Show the answer and explanation

Answer: B (II and III)

Explanation

Intensity is proportional to the square of the amplitude, not the amplitude (II wrong), and beats come from two slightly different frequencies, not different speeds (III wrong). I and IV are correct.