Question

In a region of space, a uniform magnetic field B exists in the x-direction. An electron is fired from the origin with its initial velocity u making an angle `alpha` with the y direction in the y-z plane. In the subsequent motion of the electron,

A. y-coordinate of the electron will never be negative
B. z-coordinate of the electron will never be negative
C. x-coordinate of the electron will never be negative
D. trajectory of the electron would be helical

Answer 1

Correct Answer - c
We can see from trajectory that both y- and z-coordinates
can become negative.

This trajectory lies in y-z plane. So, x-coordinate is always zero.