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COMEDK2016PhysicsWaves and Sound

90 ~dB sound is x times more intense than 40 ~dB sound, then x is

Options

  1. A5
  2. B50
  3. C10⁵
  4. D500

Correct answer

C. 10⁵

Step-by-step solution

The level of sound is given by L=10 ( I I₀ ) dB Let for 40 ~dB sound intensity be I and for 90 ~dB sound intensity be I_ x , then 40=10 ( I I₀ ) ( I I₀ )=4 ...(i) and 90=10 ( I_ x I₀ ) ( I_ x I₀ )=9 Given, I_ x =x I ( x I I₀ )=9 or x+ ( I I₀ )=9 x+4=9 [from Eq. (i)] x=5 x=10⁵

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