Nearly 10 % of the power of a 110 W light bulb is converted to visible radiation. The change in average intensities of visible radiation, at a distance of 1 m from the bulb to a distance of 5 m is a × 10 - 2 W m - 2 . The value of ' a ' will be

Step-by-step solution

Power of visible radiation is P ' = 10 100 × 110   W = 11   W Change in average intensity of visible radiation is ∆ I radiation = I radiation 1 - I radiation 2 ⇒ I 1 - I 2 = P ' 4 π r 1 2 - P ' 4 π r 2 2 = 11 4 π 1 1 - 1 25 = 11 4 π × 24 25 = 264 π × 10 - 2 = 84 × 10 - 2   W   m - 2 Hence, the value of a = 84 .