Question

A particle carrying a charge $e$ perpendicular to a uniform magnetic field of induction B with a momentum p, then the radius of the circular path is

• A. Be/p
• B. pe/B
• C. p/Be
• D. Bep

Answer 1

Answer: (C)

p/Be

Answer is C.

Force in a magnetic field
$F=qVB$

and $F=\frac{m{V}^2}{r}$ (By Newton's Law)

so, $\frac{m{V}^2}{r}=qVB$

mV = qrB

$\to r=\frac{mV}{qB}$

$=\frac{p}{Be}$ ($\because mV=pandq=e$)