Question

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 …….
A. Pm/t
B. Pt/m
C. m/Pt
D. t/mc

Answer 1

Correct Answer - B
Heat lost in t second = mL
or heat lost per second = `(mL)/t`
This must be the heat supplied for keeping the substance in matter state per second
`therefore` `(mL)/t = P` or `(Pt)/m`