4a. Define *electric field strength*.
4b. The diagram shows a pair of horizontal metal plates. Electrons can be deflected vertically using an electric field between the plates.
(i) Label, on the diagram, the polarity of the metal plates which would cause an electron positioned between the plates to accelerate upwards.
(ii) Draw the shape and direction of the electric field between the plates on the diagram.
(iii) Calculate the force on an electron between the plates when the electric field strength has a value of 2.5×103 N C−1.
4c. The diagram shows two isolated electrons, X and Y, initially at rest in a vacuum. The initial separation of the electrons is 5.0 mm.
The electrons subsequently move apart in the directions shown.
(i) Show that the initial electric force acting on each electron due to the other electron is approximately 9×10−24 N.
(ii) Calculate the initial acceleration of one electron due to the force in (c)(i).
(iii) Discuss the motion of one electron after it begins to move.
(iv) The diagram shows Y as seen from X, at one instant. Y is moving into the plane of the paper. For this instant, draw on the diagram the shape and direction of the magnetic field produced by Y.
