Q. If a charge particle enters perpendicularly in the uniform magnetic field, then:
BHUBHU 2005
Solution:
Perpendicular magnetic force exerted due to magnetic field provides the required centripetal force to the particle for motion on circular path. When a particle with charge q enters a magnetic field B, the force acting on it, is
$ F=qvB $
This provides the centripetal force to the particle.
$ qvB=\frac{m{{v}^{2}}}{R} $
Since, $ \overrightarrow{v} $ is perpendicular to $ \overrightarrow{B} $ the particle is acted upon by a force $ \overrightarrow{F} $ which is perpendicular to velocity, it does not change the magnitude of the velocity (speed) it changes only the direction of velocity. Hence, energy is constant but momentum changes.
