Question

Calculate the energy of photon (in J) of light having frequency $2.7\times {10}^{13}$ $s^{-1}$?

• A. $2\times {10}^{-21}$ $J$
• B. $1.7\times {10}^{-20}$ $J$
• C. $3.4\times {10}^{-21}$ $J$
• D. $3\times {10}^{-20}$ $J$

Answer 1

The correct option is B $1.7\times {10}^{-20}$ $J$

Given, $\lambda =2.7\times {10}^{13}$ $s^{-1}$
Energy of one photon = hv, where h=Planck's constant = $6.626\times {10}^{-34}$ $Js$
$\text{Energyof photon}=6.626\times {10}^{-34}\times 2.7\times {10}^{13}$
$=$ $17.89\times {10}^{-21}$ $J$
$=$ $1.78\times {10}^{-20}$ $J$