Fig. 9.1 illustrates a conducting ball oscillating back and forth between two charged plates. The diagram is labelled with an insulating thread, a clamp, a positive plate, a negative plate, a ball, a very high voltage supply, and a sensitive ammeter. The ball strikes each plate alternately and repeatedly.
(a)[2]
Explain, in terms of the charge on the ball, why the ball moves to the positive plate after it has struck the negative plate.
(b)[2]
State which particles pass through the sensitive ammeter and the direction of their movement.
(c)[3]
Calculate the current indicated by the sensitive ammeter.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “ball acquires -ve charge (from -ve plate)” …