a charged particle moves in a gravity free space without change in velocity. Which of the following is/are possible?

Options

A. `E ne 0, B ne 0`
B. `E = 0 , B ne 0`
C. `E ne 0, B = 0 `
D. `E = 0, B = 0 `

Answer

C

Explanation

If there is no change in the velocity, it means that the net force on the particle is zero. However, if the electric field is present, then it will apply force on the charged particle and a magnetic force would be needed to balance it. So only electric field is not possible. Only magnetic field is possible because when a particle moves parallel to the magnetic field, then it experiences no magnetic force. If both the fields are absent, then it is possible to move without any change in the velocity. Hence, option (c) is not possible in this scenrio .