Q: The energy of a photon is equal to the kinetic energy of a proton. The energy of the photon is E. Let λ1 be the de-Broglie wavelength of the proton and λ2 be the wavelength of the photon. The ratio λ1/λ2 is proportional to
(A) E0
(B) E1/2
(C) E–1
(D) E–2
Ans: (B)
Sol: $\large \frac{\lambda_1}{\lambda_2} = \frac{ \frac{h}{\sqrt{2mE}}}{ \frac{hc}{E}}$
$\large \frac{\lambda_1}{\lambda_2} \propto E^{1/2} $