Comment
Share
Q)

# About $5\%$ of the power of a low light bulb is converted to visible radiation . What is the average intensity of visible radiation , at a distance of $10\;m$. Assume that the radiation is emitted isotropic-ally and neglect reflection .

$\begin{array}{1 1} 4 \times 10^{-2} wm^{-2} \\ 4 \times 10^{-3} wm^{-2} \\ 4 \times 10^{-2} wm^{2} \\ 4 \times 10^{-3} wm^{2} \end{array}$

$I=$ Power of visible /area
$I= \large\frac{100 \times (5/100)}{4 \pi (10)^2}$
$\quad= 4 \times 10^{-3}wm^{-2}$