Question

Write a numerical expression for the emissive intensity (in W/m^2.sr) coming out of a tiny hole in an enclosure of surface temperature 1000K and emissivity 0.6:

Answer 1

6.0 ×
`10^(11)` W/
`m^(2)`

Step-by-step explanation:

From Wien's displacement formula;

Q = e A
`T^(4)`

Where: Q is the quantity of heat transferred, e is the emissivity of the surface, A is the area, and T is the temperature.

The emissive intensity =
`(Q)/(A)` = e
`T^(4)`

Given from the question that: e = 0.6 and T = 1000K, thus;

emissive intensity = 0.6 ×
`(1000)^(4)`

= 0.6 × 1.0 ×
`10^(12)`

= 6.0 ×
`10^(11)`
`(W)/(m^(2) )`

Therefore, the emissive intensity coming out of the surface is 6.0 ×
`10^(11)` W/
`m^(2)`.