Class 12 Physics
CBSE and UP Board
Dual Nature of Radiation and Matter
Chapter-11 Exercise 11.15
NCERT Solutions for Class 12 Physics Chapter 11 Question-15
What is the de Broglie wavelength of (a) a bullet of mass 0.040 kg travelling at the speed of 1.0 km/s, (b) a ball of mass 0.060 kg moving at a speed of 1.0 m/s, and (c) a dust particle of mass 1.0 × 10⁻⁹ kg drifting with a speed of 2.2 m/s?
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Ans (a).
Mass of the bullet, m = 0.040 kg
Speed of the bullet, v = 1.0 km/s = 1000 m/s
Planck’s constant, h = 6.6 x 10⁻34 Js
De Broglie wavelength of the bullet is given by the relation:
λ=h/mv
=( 6.6 x 10⁻34)/(0.040) (1000) = 1.65 x 10 ⁻³⁵ m
Ans (b).
Mass of the ball, m = 0.060 kg
Speed of the ball, v = 1.0 m/s
De Broglie wavelength of the ball is given by the relation:
λ=h/mv
=( 6.6 x 10⁻34)/(0.060) (1) = 1.1 x 10 ⁻³² m
Ans (c).
Mass of the dust particle, m = 1 x 10-9 kg
Speed of the dust particle, v = 2.2 m/s
De Broglie wavelength of the dust particle is given by the relation:
λ=h/mv
=( 6.6 x 10⁻34)/(2.2) (1 x 10-9) = 3.0 x 10 ⁻²⁵ m