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.
Given-
Diameter of the circle = 1.0 cm
Thus, radius of circle, r = = 0.5 × 10−2 m
Magnetic field, B = 0.40 T
Electric field, E = 200 V m−1
From the question we can confer that, 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 say that the electric field is balanced by the magnetic field ie,
Magnetic force, we know, Lorentz force F is given by -
where,
q = charge on an electron
v = velocity of the electron
B=magnetic field
θ= angle between B and v
The radius of the circular path described by a particle in a magnetic field r,
where,
m is the mass of a proton
v= velocity of the particle
B = magnetic force
q= charge on the particle =
C
