Q.

If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de Broglie wavelength of the particle is        [2014]

1 25  
2 75  
3 60  
4 50  

Ans.

(2)

de Broglie wavelength,

     λ=h2mK                                     ...(i)

where m is the mass and K is the kinetic energy of the particle. When kinetic energy of the particle is increased to 16 times, then its de Broglie wavelength becomes,

      λ'=h2m(16K)=14h2mK=λ4  (Using (i))

% change in the de Broglie wavelength

         =λ-λ'λ×100=(1-λ'λ)×100=(1-14)×100=75%