Question

A beam consisting of protons and electrons moving at the same speed goes through a thin region in which there is a magnetic field perpendicular to the beam. The protons and the electrons
(a) will go undeviated
(b) will be deviated by the same angle and will not separate
(c) will be deviated by different angles and hence will separate
(d) will be deviated by the same angle but will separate

Answer 1

(c) The protons and electrons will separate, i.e., they will deviate from different angles.

Explanation:

• On a charged particle, force is F = qVB
• This force for an electron is F = -eVB, whereas this force on a proton is F = eVB.
• It is to be noted that ‘e’ is the electron’s charge. So, we can observe that the protons and electrons will have equal force in different directions because of which they get separated. In other terms, it can be said that by different angles, they deviate and this leads to separation.