Q.

A photon and an electron (mass m) have the same energy E. The ratio (λphoton/λelectron) of their de-Broglie wavelengths is (c is the speed of light)         [2025]
 

1 c2mE  
2 1cE2m  
3 E2m  
4 c2mE  

Ans.

(1)

λph=hcE                                   ...(i)

λe=hp=h2mE                 ...(ii)

From eqn. (i) and (ii), we get

   λphλe=hc2mEE.h=c2mE