A black body at 227°C radiates heat at the rate of 5 cal s⁻¹ cm⁻². The rate of heat radiated at 727°C in cal s⁻¹ cm⁻² is ______.
Physics · Mixed Chapter
JEE Main Practice

Question

A black body at 227°C radiates heat at the rate of 5 cal s⁻¹ cm⁻². The rate of heat radiated at 727°C in cal s⁻¹ cm⁻² is ______.

G1 Physics · Accepted Answer

Step 1: Convert temperatures: T₁ = 227 + 273 = 500 K, T₂ = 727 + 273 = 1000 K. Step 2: Stefan–Boltzmann law for a perfect black body: radiated power per area ∝ T⁴. Step 3: H₂/H₁ = (T₂/T₁)⁴ = (1000/500)⁴ = 2⁴ = 16. Step 4: H₂ = 5 × 16 = 80 cal s⁻¹ cm⁻². Final answer: 80.