Electric Fields (AQA A Level Physics)

Two isolated point charges are separated by 60 mm, and repel each other with a force of –50 µN. If the distance between them is increased by 120 mm, what is the new force of repulsion?

An ion of mass 5.9 × 10^–17 kg and charge 2e is stationary between two charged plates.

What is the distance between the plates?

The diagram shows two particles at distance d apart. One particle has charge +2Q and the other –3Q. The two particles exert an electrostatic force of attraction, F, on each other. Each particle is then given an additional charge +Q and their separation is doubled.

Which of the following gives the force that now acts between the two particles?

Two parallel metal plates separated by a distance d of 20 cm with an electrostatic force F of 4 mN between them acting on an electron e .

What is the potential difference V midway between the plates?

The diagram shows a charge –Q being moved from point X to point Y between two charged parallel plates separated by a distance d.

Which one of the following graphs best illustrates how the electric field strength E on the charge varies with distance as it moves towards Y?

An electron travelling at constant speed enters a uniform electric field directed downwards at right angles to the field. 

Whilst the electron is in the field it accelerates:

A point charge Q is placed above an earthed metal sheet. X and Y are two points between Q and the metal sheet, as shown in the diagram.

If the electric field strengths at X and Y are  and  respectively, which one of the following statements is correct?

An ion of mass 4.6 × 10^–20 kg carrying a charge of –6.3 pC travels horizontally with a kinetic energy of 1.8 eV. 

It enters a uniform vertical electric field of strength 6500 V m^–1, which is directed downwards and acts over a horizontal distance of 23 cm.

Which one of the following rows is correct for the time for the ion to pass through the field and the magnitude of the force on the ion? 

Which one of the following cannot be used as a unit for electric field strength?

Point charges, each of magnitude Q are placed at three corners of a square as shown in the diagram

What is the direction of the resultant electric field at the fourth corner?

What is the electric field pattern between a conducting sphere and an earthed metal plate?

A +1.0 nC and 2.0 nC point charge are placed 15 cm apart. A point Q is equidistant to both charges.

If an additional charge of +2.5 nC is supplied to both charges, what is the magnitude of the electric field at Q and the direction of this field?