Question

Photons absorbed in matter are converted to heat. A source emitting n photons per second of frequency is used to convert 1 kg of ice at 0⁰ C to water a 0⁰C . Then th time T taken for the conversion :

• A. Decease with increasing n, with fixed.
• B. Decreases with n fixed,increasing .
• C. Remains constant with n andchanging such that n=constant.
• D. All of these.

Answer 1

Answer: (D)

All of these.

Answer 2

: Energy spent to convert ice into water

$= m L = ( 1000 \mathrm {~g} ) \times 80 \mathrm { cal } \mathrm { g } ^ { - 1 } = 80000 \mathrm { cal }$

Energy of photons used

$T \propto 1 / v$ when n fixed, thus t is constant if is constant. Thus options (1), (2) and (3) are correct