Question

A proton moving with a constant velocity passes through a region of space with out change in its velocity. If E and B represent the electric and magnetic fields respectively, this region may have

• A. $E=0,B\ne 0$
• B. $E\ne 0,B=0$
• C. $E$ and $B$ both parallel $
• D. $E$ and $B$ inclined at ${45}^o$ angle

Answer 1

The correct option is A $E=0,B\ne 0$

While electric field accelerates the charged particle or proton in this case, magnetic field changes it's direction.

IF the particle moves parallel to the magnetic field, no magnetic force acts on it and thus its direction does not change.

So, the region may have $E=0,B\ne 0$