Question

The velocities of two particles $A$ and $B$ are 0.05 and 0.02 $ms ^{-1}$ respectively. The mass of $B$ is five times the mass of $A$. The ratio of their de-Broglie's wavelength is

• A. 2: 1
• B. 1: 4
• C. 1: 1
• D. 4: 1

Answer 1

Answer: (A)

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

$\lambda_{ A }=\frac{ h }{ m \times 0.05}$ ;

$\lambda_{ B }=\frac{\lambda}{5 m \times 0.02}$

$\frac{\lambda_{ A }}{\lambda_{ B }}=\frac{5 m \times 0.02}{ m \times 0.05}=2: 1$