Heat energy is incident on the surface at the rate of $1000 \mathrm{~J} / \mathrm{min}$. If coefficient of…
Heat energy is incident on the surface at the rate of $1000 \mathrm{~J} / \mathrm{min}$. If coefficient of absorption is 0.8 and coefficient of reflection is 0.1 then heat energy transmitted by the surface in 5 minutes is
$100 \mathrm{~J}$
$500 \mathrm{~J}$
$700 \mathrm{~J}$
$900 \mathrm{~J}$
Solution
Let, heat transmitted per minute be $\mathrm{H}$
Now,
Energy incident=energy absorbed+energy reflected+energy transmitted
$\begin{aligned}
& \Rightarrow 1000=0.8 \times 1000+0.1 \times 1000+\mathrm{H} \\
& \Rightarrow \mathrm{H}=100 \mathrm{~J} / \mathrm{min}
\end{aligned}$
Heat energy transmitted in 5 minutes $=100 \times 5=500 \mathrm{~J}$