Question

Heat energy is incident on the surface at the rate of $1000J/min$. 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

• A. $100$J
• B. $500$J
• C. $700$J
• D. $900$J

Answer 1

Answer: (B)

$500$J

Let, heat transmitted per minute be $H$

Now,

Energy incident=energy absorbed+energy reflected+energy transmitted

$⟹1000=0.8\times 1000+0.1\times 1000+H$

$⟹H=100J/min$

Heat energy transmitted in 5 minutes= $100\times 5=500J$

Hence, answer is option-(B).