Photons absorbed in matter are converted to heat. A source emitting n photons/ sec of frequency `nu` is used to convert 1kg of ice at `0^(@)C` to water at `0^(@)C`. Then, the time T taken for the conversion

Options

A. decreases with increasing `n`, with `v` fixed.
B. decreases with `n` fixed, `v` increasing.
C. remains constant with `n` and `v` changing such that `nv`=constant.
D. increase when the product `nv` increases

Answer

A, B, C

Explanation

`T = ("Required energy to convert 1kg of ice at" 0^(@)C)/("Energy emitted by the source per second") = (mL)/(mhv)`
`therefore T prop 1/n`,when `v` is constant.
`T prop 1/v'` when `n` fixed ,`T prop 1/(nv)`
Thus `T` is constant only if `nv` is constant.