Question

A positively charged particle moving in east direction enters a region of uniform magnetic field directed vertically upwards. What will be the path of the particle ?

• A. get deflected in vertically upward direction
• B. move in circular path with an increased speed
• C. move in circular path with a decreased speed
• D. move in a circular path with a uniform speed

Answer 1

The correct option is D move in a circular path with a uniform speed

If a positively charged particle moving in east direction enters a region of uniform magnetic field directed vertically upwards, it will move in a circular path with a uniform speed.
If a charged particle is moving in a direction perpendicular to a uniform magnetic field, then its trajectory will be a circle because the force $F=qvB$ is always perpendicular to the velocity, and therefore centripetal.