Asked in MDCAT Test Series 5 — Waves and Thermodynamics (7 March 2025) 2025Moderate

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.

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