# A Particle Moves in a Circle of Diameter 1.0 Cm Under the Action of a Magnetic Field of 0.40 T. an Electric Field of 200 V M−1 Makes the Path Straight. Find the Charge/Mass Ratio of the Particle. - Physics

Sum

A particle moves in a circle of diameter 1.0 cm under the action of a magnetic field of 0.40 T. An electric field of 200 V m−1 makes the path straight. Find the charge/mass ratio of the particle.

#### Solution

Given:
Diameter of the circle = 1.0 cm
Thus, radius of circle, = = 0.5 × 10−2 m,
Magnetic field, B = 0.40 T
Electric field, E = 200 V m−1.
As per the question, the particle is moving in a circle under the action of a magnetic field. But when an electric field is applied on the particle, it moves in a straight line.
So, we can write:
Fe = Fm
qE = qvB, where q is the charge and v is the velocity of the particle.
⇒ v = E/B = 200/0.4 = 500 m//s
As r = v/(rB)
=500/(0.5xx10^-2xx0.4)
= 2.5 × 105 c /kg

Concept: Force on a Moving Charge in Uniform Magnetic and Electric Fields
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 12 Magnetic Field
Q 47 | Page 234