Question

(a) Write the expression for the magnetic force acting on a particle moving with velocity v in the presence of magnetic field B.
(b) A neutron an electron and an alpha particle moving with equal velocities enter a uniform magnetic field going into the plane as shown. Trace their paths in the field and justify your answer.

Answer 1

We know that,

$F=qVB$

Where, F= force,q= charge,V= velocity and B= magnetic field and

$F=\frac{m{V}^2}{r}$; m=mass, V= velocity, r= radius.

$\therefore \frac{m{V}^2}{r}=qVB$

For electron q=-ve and m=me

Thus circular path.

For alpha, q= +ve, m=mp

Thus circular and larger radii, but neutron has q=0, thus continue in initial velocity.