A proton moving in a straight line enters a strong magnetic field in a direction parallel to the field. What will be the change in its speed and the direction of motion on moving the magnetic field?

Explanation

When a proton enters a strong magnetic field along the field direction, i.e., `theta = 0^(@)` , the force experienced by proton is `F = qvB sin theta = qvB sin^(@) =0`. Therefore, the path and velocity of the proton will remain unchanged.