Capacitor Questions
Q1. The graph shows how the charge of a capacitor varies with the p.d. across it.
Use the graph to find -
a) the energy stored by the capacitor when charged to a potential difference of 8 V
Area under graph (equiv to ½ QV) = energy
Mark for marking the line on the graph to outline the area to be calculated
E = ½ x 3.5 x 10-3 x 8
E = 0.014 J
(3 marks)
b) the capacitance of the capacitor
Gradient of the graph = Q/V = C
Mark for using a 'large' triange - smallest side 8 cm
gradient = Δy/Δx
C = (3.5 x 10-3 - 0.0)/ (8.0 - 0.0)
C = 4.4 x 10-4 F
(3 marks)
(Total 6 marks)