Physics · Electrostatics

The formula for Electric Field is given by;

E = F/q

Where, according to Newton's second law of motion, F = ma

E = ma/q

In the problem, the proton is suspended in a gravitational field, where F = W = mg, and acceleration

becomes acceleration due to gravity 'g'

we get,

E = mg/q

This is the correct option. The electric field strength (E) is equal to the gravitational acceleration (g) multiplied by the mass of the proton (m) and divided by the charge of the proton (q). This equation represents the balance between the gravitational force and the electric force acting on the proton.

This option is incorrect. The presence of the variable "v" suggests that it represents velocity. However, velocity is not relevant to finding the magnitude of the electric field in this context. The equation does not include any justification for dividing by velocity.

This option is incorrect. Similar to the previous option, the variables "v" and "B" are not defined and do not relate to finding the magnitude of the electric field. The presence of "B" suggests it may refer to a magnetic field, but there is no indication of how it relates to the problem.

This option is incorrect. It incorrectly swaps the positions of the charge (q) and the mass (m) in the equation. The correct equation should have the mass (m) in the numerator and the charge (q) in the denominator.