Question

The temperature of a piece of iron is ${27}^0$ C and it is radiating energy at the rate of Q kWm-2. If its temperature is raised to ${151}^0$ C, the rate of radiation of energy will become approximately

• A. 2Q kWm-2
• B. 4Q kWm-2
• C. 6Q kWm-2
• D. 8Q kWm-2

Answer 1

The correct option is B

4Q kWm-2

$E_2=E_1\frac{T_2^4}{T_1^4}=Q\times \frac{(273+151{)}^4}{(273+27{)}^4}={\left(\frac{424}{300}\right)}^4=3.99Q\approx 4Q$