Electric Fields - exam practice

1.5 mJ of work is done when a charge of 30 µC is moved between two points, M and N, in an electric field.

What is the potential difference between M and N?

The ionisation potential for the atoms of a gas is V. Electrons of mass m and charge e travelling at a speed v can just cause ionisation of atoms in the gas.

What is v?

A positive charge of 2.0 × 10⁻⁴ C is placed in an electric field at a point where the potential is +500 V.

What is the potential energy of the system?

An ion is accelerated by a series of electrodes in a vacuum. A graph of the power supplied to the ion is plotted against time.

What is represented by the area under the graph between two times?

Two protons are separated by distance r.

The electrostatic force between the two protons is X times the gravitational force between them.

What is the best estimate for X?

The diagram shows the path of a proton being deflected by the nucleus of an atom.

Point P is the position of the proton when it is closest to the nucleus.

What is not true about the proton along its path at P?

A particle of mass m and charge q is accelerated through a potential difference V over a distance d.

What is the average acceleration of the particle?

An electron moves through a distance of 0.10 m parallel to the field lines of a uniform electric field of strength 2.0 kN C⁻¹.

What is the work done on the electron?

The electric potential at a distance r from a positive point charge is 45 V. The potential increases to 50 V when the distance from the point charge decreases by 1.5 m. What is the value of r?

A small object of mass m has a charge Q. The object remains stationary in an evacuated space between two horizontal plates. The plates are separated by a distance d and the potential difference between the plates is V.

What is V?