Question

A ball of mass 0.5kg is moving with velocity 6.626 m/s. What’s the wavelength of that ball?

(a) 1 x 10^-34 m

(b) 2 x 10^-34 m

(c) 2 x 10^-32 m

(d) 2 x 10^-3 m

I got this question during an interview for a job.

Question is taken from Towards Quantum Mechanical Model of the Atom in section Structure of Atom of Chemistry – Class 11

Answer 1

Correct option is (b) 2 x 10^-34 m

The explanation is: Louis de Brogie gave the realation between momentum and wavelength as λ = h/p. Here h is Planck’s constant, whose value is 6.626 x 10^-34 J/s. Wavelength = h/mv = 2 x 10^-34 m (momentum p = mass m x velocity v).