Question

Find the number of photons of radiation of frequency $5\times {10}^{13}{s}^{-1}$ that must be absorded in order to melt one gm ice when the latent heat of fusion of ice is $330j/g$. $(h=6.6\times {10}^{-34}j\times sec.)$

Answer 1

$E=n\times h\times f$

n-number of photons, h-planks constant, f- frequeny.

substituting the values in the above equation,

$330=n\times 6.626\times 10^{-34}\times 5\times 10^{13}$

$n=\frac{330\times 10^{34}}{6.626\times 5\times 10^{13}}=9.96\times 10^{21}$

conclusion: hence the number of photons is $n=9.96\times 10^{21}$