JEE PYQ: Atomic Physics Question 17
Question 17 - 2021 (25 Feb Shift 1)
An $\alpha$ particle and a proton are accelerated from rest by a potential difference of 200 V. After this, their de Broglie wavelengths are $\lambda_\alpha$ and $\lambda_p$ respectively. The ratio $\frac{\lambda_p}{\lambda_\alpha}$ is:
(1) 8
(2) 2.8
(3) 3.8
(4) 7.8
Show Answer
Answer: (2)
Solution
$\lambda = \frac{h}{p} = \frac{h}{\sqrt{2mqV}}$. $\frac{\lambda_p}{\lambda_\alpha} = \sqrt{\frac{m_\alpha q_\alpha}{m_p q_p}} = \sqrt{\frac{4 \times 2}{1 \times 1}} = 2\sqrt{2} = 2.8$.
BETA
