Question

Assertion: The centre of mass of an electron and proton, when released moves faster towards proton.
Reason : This is because proton is heavier.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

As $qE=\frac{m{v}^2}{r}$,
$r=\frac{m{v}^2}{qE}$
$=\frac{2K}{qE}$
(where $K=\frac{1}{2}m{v}^2$
i.e, $r\propto \frac{1}{q}$
Since electron and proton have equal charge, r is the same for both of them
Here, $r$ depends on $K$ (which is given to be the same for both the particles) and as such not on their masses