### NEET Solved Paper 2019 Question 4

##### Question: Ionized hydrogen atoms and $ \alpha $ -particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths $ r _{H}:{r _{\alpha }} $ will be: [NEET 5-5-2019]

#### Options:

A) 4 : 1

B) 1 : 4

C) 2 : 1

D) 1 : 2

## Show Answer

#### Answer:

Correct Answer: C

#### Solution:

$ r=\frac{mv}{qB}=\frac{p}{qB} $

$ r\propto \frac{1}{q} $

$ \frac{r _{H}}{{r _{\alpha }}}=\frac{{q _{\alpha }}}{q _{H}}=\frac{2e}{e} $

$ r _{H}:{r _{\alpha }}=2:1 $