Six original Cambridge-style questions on the uniform field E = V / d between parallel plates, charges accelerated across it, and the parabolic path of a charge fired through it.
Two parallel metal plates are 12 mm apart and have a potential difference of 450 V between them. Calculate the electric field strength between the plates and the force on a proton placed between them.
Explain what is meant by the statement that the electric field between two parallel charged plates is uniform, and describe how this is shown in a diagram of the field lines.
An electron is released from rest at the negative plate of a pair of parallel plates 2.0 cm apart with a potential difference of 800 V between them. Calculate the kinetic energy and the speed of the electron as it reaches the positive plate, and the time it takes to cross the gap.
An electron travelling at 2.5 × 10⁷ m s⁻¹ enters the uniform field between two horizontal plates, midway between them and parallel to them. The plates are 50 mm long and 20 mm apart, and the potential difference between them is 120 V. Determine whether the electron leaves the field without striking a plate, and calculate the angle its velocity makes with its original direction as it leaves.
An electron and a proton enter the same uniform electric field at the same point with the same velocity, perpendicular to the field. Compare the forces on them and the paths they follow while in the field.
In an oil-drop experiment a drop of mass 2.4 × 10⁻¹⁵ kg is held stationary between two horizontal plates 5.0 mm apart when the potential difference between them is 245 V, with the upper plate positive.
(a) Calculate the electric field strength between the plates. (b) Calculate the charge on the drop. (c) State the sign of the charge and the number of electrons it corresponds to.
Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.