Question

How alpha beta particles travel in uniform magnetic field?

Answer 1

Alpha and beta move in circular paths in a magnetic field. In magnetic fields charged particles tend to move in circles. This is because the force is always at right angles to the direction the particle is moving at each instant as it curves. therefore Lorentz Force is equal to centripetal force so

Lorentz Force=centripetal force
$qvb = \frac{ {mv}^{2} }{r} \\ \frac{qvb}{v} = \frac{mv}{r} \\ qb = \frac{p}{r} \\ qrb = p \\ qrb = momentum$