If the amplitude is 200, the intensity is 300. When the amplitude is increased to 800, then what will be the intensity?

Correct answer: E. 4800

  • A. 1200
  • B. 1400
  • C. 1600
  • D. 1800
  • E. 4800

Explanation

We know that The intensity of a wave is directly proportional to the square of its amplitude Mathematically-> I x a2HereI = intensitya = amplitudeAccording to the question, we are asked to find the new intensity given that If the amplitude is 200, the intensity is 300. When the amplitude is increased to 800HenceI = 300a = 200a' = 800Increase in amplitude (A)-> A = a'/aHence-> A = 800/200On further simplificationWe get-> A = 4Increase in amplitude (squared)-> A2 = 42-> A2 = 16Amplitude squared increases by a factor of 16-> I' = I x A2HereI' = new intensityI = initial intensityA² = squared amplitude factorIf the amplitude is 200, the intensity is 300. When the amplitude is increased to 800.HenceI = 300 We found out thatA² = 16Substituting the values-> I' = 300 x 16On further simplification-> I' = 4800HenceNew intensity = 4800When the amplitude is increased to 800 then the intensity will be 4800.

This question appeared on the NUMS 2016 paper, which you can sit online with every answer explained.

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