If the energy of a photon is 1 eV, what is wavelength of that photon?

(কোন একটি ফোটনের শক্তি 1 eV হলে ঐ ফোটনের তরঙ্গ দৈর্ঘ্য কত?)

এখানে,

$\begin{array}{l} \mathrm{E}=1 \mathrm{eV} \\ =1.6 \times 10^{-19} \mathrm{~J} \\ \mathrm{C}=3 \times 10^{8} \mathrm{~ms}^{-1} \\ \mathrm{h}=6.626 \times 10^{-} { }^{34} \mathrm{~J} . \mathrm{s} \\ 1 \mathrm{~nm}=10^{-9} \mathrm{~m} \\ \therefore 1 \mathrm{~m}=10^{9} \mathrm{~nm} \end{array}$

$\begin{aligned} & E=h v=h \frac{c}{\lambda} \\ \Rightarrow & \lambda=\frac{h c}{E} \\ = & \frac{\left(6.626 \times 10^{-34}\right) \times\left(3 \times 10^{8}\right)}{1.6 \times 10^{-19}} \\ = & 1.242 \times 10^{-6} \mathrm{~m} \\ = & 1.242 \times 10^{-6} \times 10^{9} \mathrm{~nm}=1242 \mathrm{~nm}\end{aligned}$