6 Two positively charged identical metal spheres A and B have their centres separated by a distance of 24 cm, as shown in Fig. 6.1. [Figure 6.1] The variation with distance x from the centre of A of the electric field strength E due to the two spheres, along the line joining their centres, is represented in Fig. 6.2. [Figure 6.2]

1. (a)State the radius of the two spheres. radius = ................................................................ cm [1][1]
2. (b)The charge on sphere A is 3.6 × 10⁻⁹C. Determine the charge Q_B on sphere B. Assume that spheres A and B can be treated as point charges at their centres. Explain your working. Q_B = ........................................................................ C [3][3]
3. (c)(i)Sphere B is removed. Use information from (b) to determine the electric potential on the surface of sphere A. electric potential = ................................................................ V [2][2]
4. (c)(ii)Calculate the capacitance of sphere A. capacitance = ................................................................ F [2][2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.