Question

Complete the following: __________ radiation deviates minimum in a magnetic field.

• A. Alpha
• B. Beta

Hint:

Think of it like throwing a bowling ball (Alpha) and a ping-pong ball (Beta) through a strong cross-wind (magnetic field). The much heavier bowling ball will deviate far less.

Answer 1

The Correct Option is A

The force experienced by a charged particle moving in a magnetic field is given by \(F = qvB\). The subsequent acceleration is \(a = F/m = (qvB)/m\). The amount of deviation or the radius of the circular path depends on the charge-to-mass ratio (\(q/m\)).
- Alpha particles (\(He^{2+}\)) are relatively heavy (4 amu) and have a charge of +2e.
- Beta particles (\(e^-\)) are extremely light (approx 1/1836 amu) and have a charge of -1e.
The charge-to-mass ratio for a beta particle is much larger than for an alpha particle. Due to their much larger mass (and thus inertia), alpha particles are deflected much less than beta particles for a given magnetic field and velocity. Therefore, alpha radiation deviates the minimum.