Question

A charged particle moves uniformly through some region of space, meaning it travels at a constant velocity. From this information, can we rule out the presence of an electric field within this region? Why or why not?

Can we rule out the presence of a magnetic field within this region? Why or why not?

Answer 1

There is possibility such that both the electric and magnetic field present or only magnetic field is present in the region.

Case 1: When both the field is present.

In this case magnetic field should not be along the direction of the motion of charge particle. In such case, magnetic field exerts a magnetic force which will be perpendicular to the direction of velocity and magnetoc field itself. So there has to be an electric field opposite (considering +ve charge) this direction (direction of force) which will balance the magnetic force by the electric force. Hence when net force become zero, particle will move with constant velocity.

Case 2: When only magnetic field is present, it should be along the direction of motion so that it cant exert any force on the particle.