A particle carrying a charge of +e travels in a circular path of radius R in a uniform magnetic field.If instead the particle carried a charge of +2e,the radius of the circular path would have been
A)2R.
B)4R.
C)8R.
D)R/2.
E)R/4.

Question

Quizplus · Accepted Answer

The radius of the circular path $r$ for a charged particle moving in a magnetic field is given by $r = \frac{mv}{qB}$, where $m$ is the mass of the particle, $v$ is its velocity, $q$ is its charge, and $B$ is the magnetic field strength. Doubling the charge ($q$ becomes $2e$) while keeping the other factors constant (assuming the kinetic energy and thus the velocity of the particle remains the same) would halve the radius of the path, making the correct answer $R/2$.

A Particle Carrying a Charge of +E Travels in a Circular