Question

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

Answer 1

Energy $=nh\nu$

where, $n=$ number of photons

$h=$ Plank's constant $=6.6\times {10}^{-34}$ $Jsec$

$\nu =$ Frequency

$\therefore 330=n\times 6.6\times {10}^{-34}\times 5\times {10}^{13}$

$\therefore n=\frac{330}{6.6\times {10}^{-34}\times 5\times {10}^{13}}$

$\therefore n=1\times {10}^{22}$ photons

Therefore the number of photons is ${10}^{22}$