Q. A particle$\ $A has a charge q and particle$\ $B has charge+4q with each of them having the mass m. When they are allowed to fall from rest through same potential difference, the ratio of their speeds $v_{A}:v_{B}$ will be

A) 4:1
B) 1:4
C) 1:2
D) 2:1
Explanation

(c) Speed obtained by the particle after falling through a potential difference of $V$ volt is
$v_{A} = \sqrt{\frac{2Vq}{m}}\ \ \ldots(i)$
And $v_{B} = \ \sqrt{\frac{2V \times 4q}{m}}$ …(ii)
Now dividing Eq. (i) by Eq. (ii), we get
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{v_{A}}{v_{B}} = \sqrt{\frac{1}{4}}$=$\frac{1}{2}$
So, $v_{A}:v_{B} = 1:2$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.