Question

Heat energy is incident on the surface at the rate of 1000 J/min. If the coefficient of absorption is 0.8 and the coefficient of reflection is 0.1 then heat energy transmitted by the surface in 5 minutes is ______.

Options

• 100J

• 500J

• 700J

• 900J

Answer 1

Heat energy is incident on the surface at the rate of 1000 J/min. If the absorption coefficient is 0.8 and the reflection coefficient is 0.1 then the heat energy transmitted by the surface in of 5 minutes is 500J.

Explanation:

r + a + t = l

∴ t = 1 − r − a

= 1 − 0.8 − 0.1

= 1 − 0.9

= 0.1

Q = 1000 J/min

∴ Heat energy transmitted per minute

Q_t = Q × t

= 1000 × 0 .1

= 100J

∴ Heat energy transmitted in 5 minutes

= 100 × 5

= 500J