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JAMB Physics 2007 Question 2

Question 2

Sound

The fundamental frequency of a plucked wire under a tension of 400 N is 250 Hz. When the frequency is changed to 500 Hz at constant length, the tension is

  1. A.40 N.
  2. B.160 N.
  3. C.400 N.
  4. D.1600 N.
Show the answer and explanation

Answer: D (1600 N.)

Explanation

For a stretched wire f ∝ √T. Doubling the frequency (250 Hz to 500 Hz) needs four times the tension: 4 × 400 N = 1600 N.