Question

A proton and an electron are placed in a uniform electric field.

Options

• The electric forces acting on them will be equal.

•  The magnitudes of the forces will be equal.

•  Their accelerations will be equal.

• The magnitudes of their accelerations will be equal.

Answer 1

The magnitudes of the forces will be equal.
We know: \[\vec{F}  = q \vec{E}\]  For an electron and a proton, the value of q will be same, but the sign will be opposite.
Hence, they will experience a force that will be equal in magnitude but opposite in direction.
Now,

\[\vec{F} = q \vec{E} = m \vec{a} \]
\[ \Rightarrow \vec{a} = \frac{q \vec{E}}{m}\]

As the electron and proton have different values of mass m, they will have different magnitudes of acceleration. Also, they will differ in direction due to the opposite signs of q.