Question

This section contains multiple choice questions. Each question has 4 choices (a), (b), (c) and (d ) out of which ONE OR MORE may be correct.

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively, Identify which of the following options can be true for the space.

• A. $E=0,B=0$
• B. $E=0,B\ne 0$
• C. $E\ne 0,B=0$
• D. $E\ne 0,B\ne 0$

Answer 1

Answer: (A), (D)

A proton moving through a space contain electric and magnetic field will experience a force
$F=q(\overrightarrow{E}+\overrightarrow{v}\times \overrightarrow{B})$
If the proton passes through the space without changing its velocity then two cases can be possible:
i) either $E=0$ and $B=0$. (Trivial case)
ii) or, $E\ne 0$ and $B\ne 0$ (motion of the proton (v) is perpendicular to the B)