Question

Calculate the energy in joule corresponding to light of 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. $4.42\times {10}^{-15}$
• B. $4.42\times {10}^{-18}$
• C. $6.67\times {10}^{15}$
• D. $6.67\times {10}^{11}$

Answer 1

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

As We know,
Energy $=\frac{hc}{\lambda }=\frac{6.6\times {10}^{-34}\times 3\times {10}^8}{45\times {10}^{-9}}=0.44\times {10}^{-17}$

$=4.4\times {10}^{-18}\text{Joule}$
$\therefore$ The correct option is (b).