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 b changing such that nv= constant
D. increases when the product nv increases

Explanation

Energy spent to convert ice into water
`" "` = mass x laten heat
`" "=mL=(1000g)xx(80cal//g)`
`" "` = 80000 cal
Energy of photons used `=nTxxE=nTxxhv`
`So, " "nThv=mLimpliesT=(mL)/(nhv)" "[becauseE=hv]`
`therefore " "Tprop1/n,` when n is fixed.
`therefore " "Tprop1/v,` when n is fixed.
`impliesTprop1/(nv)`
Thus, T is constant, if nv is constant.