A substance of mass M kg requires a power input of P wants to remain in the molten state at its melting point. When the power source is turned off, the sample completely solidifies in time t seconds. The latent heat of fusion of the substance is …….

Options

A. `(Pm)/(t)`
B. `(Pt)/(m)`
C. `(m)/(Pt)`
D. `(t)/(Pm)`

Answer

B

Explanation

Heat lost in `t sec = mL` or heat lost per sec = `(mL)/(t)`. This must be the heat supplied for keeping the substance in molten state per sec.
`:. (mL)/(t) = P or L = (Pt)/(m)`.