Q.

The de Broglie wavelength of an electron having kinetic energy E is λ. If the kinetic energy of electron becomes E4, then its de-Broglie wavelength will be          [2023]

1 λ2  
2 λ2  
3 2λ  
4 2λ  

Ans.

(3)

λ=h2mE

λ'=h2m(E4)=2h2mE=2λ