For a perfectly black body, coefficient of emission is (a) zero. (b) unity. (c) less than one (non-zero). (d) infinity.

Answer: (b). A perfectly black body absorbs all radiation ( a = 1), and by Kirchhoff's law e = a. So the answer is (b) unity.

For a perfectly black body, coefficient of emission is | MHT CET 2025 (20 Apr, Shift 1)

Q40MHT CET 2025 · 20 APR · SHIFT 1Easy

Thermal Radiation: Black Body, Stefan & Wien

For a perfectly black body, coefficient of emission is

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Answer: (b)

A perfectly black body absorbs all radiation ( $a = 1$ ), and by Kirchhoff's law $e = a$ .
So the answer is (b) unity.

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