Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have seen in Exercise 11.31, an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain.

(mn = 1.675 × 10–27 kg)

Given:


Kinetic energy of neutron, E = 150 eV = 150 × 1.6 × 10-19


E = 2.4 × 10-17 J


Mass of neutron, mn = 1.675 × 10-27 Kg


Kinetic energy of a particle is given by,



We can write,


mv = (2 × m × KE)0.5


P = (2 × m × KE)0.5 ...(1)


Where,


m = mass of electron


v = velocity of electron


p = momentum of particle


By putting the equation (1) in de- Broglie equation, we get,


…(2)


Now substituting the values in eq (2) we get,



λ = 2.327 × 10-12m


A neutron cannot be used in diffraction experiment as lattice spaces are of the order of few 10-10 m, whereas the wavelength of a neutron beam is 100 times smaller.


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