Question

7.57 What is the wavelength of a neutron traveling at a speed of 4.15 km/s? (Neutrons of these speeds are obtained from a nu- clear pile.)

Answer 1

7.57

de Broglie wavelength,

$\lambda =\frac{h}{mv}$

where,

h = Planck's constant = 6.626 x 10^-34 J.s

m = mass of a neutron = 1.675 ×10⁻²⁷ kg

= speed of the neutron = 4.15 km/s = 4150 m/s             ($\because$ 1 km = 1000 m)

Thus, the wavelength of the neutron,

$\lambda$ = 6.626 x 10^-34 J.s / (1.675 ×10⁻²⁷ kg x 4150 m/s )

   = 9.53 x 10^-11 m

Hence, the wavelength of the neutron = 9.53 x 10^-11 m