A kiln door is opened

PHYSICS · Subjective · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A kiln door is opened, exposing a

0.10\,\text{m}^2

ceramic slab to the room. For the first

30\,\text{s}

, the slab remains at

1400\,\text{K}

. During the next

90\,\text{s}

, its temperature decreases linearly to

800\,\text{K}

. Assuming the slab is an ideal blackbody throughout, calculate the total energy it radiates during the entire

120\,\text{s}

interval. Use

\sigma = 5.67 \times 10^{-8}\,\text{W m}^{-2}\,\text{K}^{-4}