Dual Nature Of Matter Question 1

Question 1 - 2024 (01 Feb Shift 1)

The de Broglie wavelengths of a proton and an $\alpha$ particle are $\lambda$ and $2 \lambda$ respectively. The ratio of the velocities of proton and $\alpha$ particle will be :

(1) $1: 8$

(2) $1: 2$

(3) $4: 1$

(4) $8: 1$

Show Answer

Answer: (4)

Solution:

$\lambda=\frac{h}{p}=\frac{h}{mv} \Rightarrow v=\frac{h}{m \lambda}$

$\frac{v _p}{v _{\alpha}}=\frac{m _{\alpha}}{m _p} \times \frac{\lambda _{\alpha}}{\lambda _p}$

$=4 \times 2=8$