NEET Questions Solved

NEET - 2017

The de-Brogile wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is 

(a)hmkT

(b)h3mkT

(c)2h3mkT 

(d)2hmkT

(b) Thinking Processs de-Brogile wavelength associated with a moving particle can be given as 

 λ=hp=h2m(K.E)

At thermal equilibrium,temperature of neutron and heavy water will be same. This common temperature is given as, T. Also, we know that, kinetic energy of a particle 

              KE=p22m

    where, p=momentum of the particle 

 m=mass of the particle

Kinetic energy of the neutron is 

     KE=32kT

  de-Brogile wavelength of the neutron 

      λ=hp=h2m(K.E)

   =h2m×32kT=h3mkT

Difficulty Level:

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