Question

Heat energy is incident on the surface at the rate of 2000 J/min. If coefficient of absorption is 0.8 and coefficient of reflection is 0.1 then heat energy transmitted by the surface in 10 minutes is ____________.

Options

• 2000 J

• 500 J

• 700 J

• 1000 J

Answer 1

Heat energy is incident on the surface at the rate of 2000 J/min. If coefficient of absorption is 0.8 and coefficient of reflection is 0.1 then heat energy transmitted by the surface in 10 minutes is 2000 J.

Explanation:

r + a + t_r = 1

∴ tr = 1 - r -a

= 1 - 0.8 - 0.1

= 1 - 0.9

= 0.1

∴ Q = 2000 J/min

∴ Heat energy transmitted per minute

Q_t = Q x t

= 2000 x 0.1

= 200 J

∴ Heat energy transmitted in 5 minutes

= 200 x 10

= 2000 J