Question

A homogeneous electric field $\overrightarrow{E}$ and a uniform magnetic field $\overrightarrow{B}$ are pointing in the same direction. A proton is projected with its velocity parallel to $\overrightarrow{E}.$ It will

• A. go on moving in the same direction with increasing velocity
• B. go on moving in the same direction with constant velocity
• C. turn to its right
• D. turn to its left

Answer 1

The correct option is A go on moving in the same direction with increasing velocity

Here magnetic force is zero(as velocity is parellel to Magnetic field $\overrightarrow{F}=q(\overrightarrow{V}\times \overrightarrow{B})$,
but the velocity increases due to electric force$\overrightarrow{F}=q\left(\overrightarrow{E}\right)$.