Question

Sun’s surface at 5800 K emits radiation at a wavelength of 0.5 μA. A furnace at 300°C will emit through a small opening, radiation at a wavelength of
1. 5 μA
2. 0.5 μA
3. 2.5 μA
4. 0.25 μA

Answer 1

Correct Answer - Option 1 : 5 μA

Concept:

Wein’s displacement law:

It states that the “product of absolute temperature and wavelength at which emissive power of a black body is a maximum, is constant”.

λmax.T = 2898 μmK

i.e. λ₁T₁ = λ₂T₂ 

Calculation:

Given:

T₁= 5800 K, λ₁ = 0.5 μA, T₂ = 300°C = 573 K

⇒ 0.5 × 5800 = λ₂ × (573)

λ₂ = 5.06 μA