Q11 / 160 · AP EAMCET 2006 · Chemistry

The energy of a photon is $3 \times 10^{-12}$ ergs. What is its wavelength in $\mathrm{nm}$ ? $\text { ( } h=6.62 \times 10^{-27} \text { ergs-s; } c=3 \times 10^{10} \mathrm{~cm} / \mathrm{s} \text { ) }$

  • Correct answer
    A
    662
  • B
    1324
  • C
    66.2
  • D
    6.62

Solution

$E=3 \times 10^{-12}$ ergs. $\lambda=$ ? $h=6.62 \times 10^{-27}$ erg-s $c=3 \times 10^{10} \mathrm{cms}^{-1}$ $E=\frac{h c}{\lambda}$ $3 \times 10^{-2}=\frac{6.62 \times 10^{-27} \times 3 \times 10^{10}}{\lambda}$ $\lambda=\frac{6.62 \times 10^{-27} \times 3 \times 10^{10}}{3 \times 10^{-12}}$ $=6.62 \times 10^{-5} \mathrm{~cm}$ $=662 \times 10^{-7} \mathrm{~cm}$ $=662 \times 10^{-9} \mathrm{~m}$ $=662 \mathrm{~nm}$

Hence, the correct answer is option: 'A'.

Relevant Questions