Q109 / 160 · JIPMER 2009 · Physics

A sound absorber attenuates the sound level by 20 dB . The intensity decreases by a factor of

  • A
    1000
  • B
    10000
  • C
    10
  • Correct answer
    D
    100

Solution

Let intensity of sound be $I$ and $I^{\prime}$ Loudness of sound initially $\beta_1=10 \log \left(\frac{I}{I_0}\right)$ Later, $\beta_2=10 \log \left(\frac{I^{\prime}}{I_0}\right)$ Given, $\beta_2-\beta_1=20$ $\therefore \quad 20=10 \log \left(\frac{I^{\prime}}{I}\right)$ $\therefore \quad I^{\prime}=100 I$

Hence, the correct answer is option: 'D'.

More Waves and Sound Questions