Question

Calculate the energy of the light having wavelength 45 nm :

[Planck's constant $h=6.63\times {10}^{-34}Js$ ; speed of light $c=3\times {10}^{8}m{s}^{-1}$]

• A. $6.67\times {10}^{15}$
• B. $6.67\times {10}^{11}$
• C. $4.42\times {10}^{-15}$
• D. $4.42\times {10}^{-18}$

Answer 1

The correct option is D $4.42\times {10}^{-18}$

The relationship between the enrgy of light and its wavelength is as given below.

$E=\frac{hc}{\lambda }$

Substitute values in the above expression.

$E=\frac{6.63\times {10}^{-34}\times 3\times {10}^8}{45\times {10}^{-9}}=4.4\times {10}^{-18}$

Hence, the energy of light corresponding to wavelength 45 nm is $4.42\times {10}^{-18}$.

Hence, the correct option is $D$