Electric Fields (Edexcel A Level Physics): Exam Questions

The distance between a proton and an electron is r. The electrostatic force is F.

The distance between the proton and electron is doubled.

Which of the following is equal to the electrostatic force at this separation?

A potential difference is applied across two parallel plates. A particle carrying a charge of +0.1 C is placed between the plates and experiences a force F.

The distance between the plates is halved. The potential difference remains constant.

Which of the following is now equal to the electric field strength between the plates?

A potential difference V is applied across two parallel plates. An electron midway between the two plates at point X experiences an electric force F.

The electron moves to point Y which is halfway between point X and the left-hand plate.

Which of the following is the electric force experienced by the electron at Y?

The diagram shows an oil droplet of mass $m$ between two parallel metal plates separated by a distance $d$. The upper plate is at potential $+V$ and the lower plate is at potential $-V$. The droplet is stationary.

What is the magnitude of the charge on the droplet?

Two charged spheres carry charges of $+4.0\times {10}^{-9}\text{ C}$ and $+2.0\times {10}^{-9}\text{ C}$. The distance between the centres of the spheres is $0.060\text{ m}$.

Which expression gives the magnitude of the force, in newtons, on each sphere?

The diagram shows the electric field lines around a point charge.

Which of the following diagrams best represents the equipotential lines around the point charge?

The graph shows how an electric potential V varies with distance x.

Which of the following shows the corresponding variation of electric field strength E with x?

A charge of $3.0\text{ μC}$ is moved from the 400 V equipotential of an electric field to the 150 V equipotential. It is then moved a distance of $0.20\text{ m}$ along the 150 V equipotential.

What is the magnitude of the total work done on the charge?