Physics 9702 · AS & A Level · Electric potential

Electric potential — practice question

A charged metal sphere is placed in isolation in space. The electric potential $V$ is measured at a range of distances $x$ from the sphere’s centre. Figure 5.1 shows how the potential $V$ changes with distance $x$.
(a)[3]

From Fig. 5.1, calculate the electric field strength, in $\text{N C}^{-1}$, at $x = 4.0\,\text{cm}$. Show your steps.

(b(i))[1]

The sphere carries a charge of $8.0 \times 10^{-9}\,\text{C}$. Use Fig. 5.1 to state the electric potential at the sphere’s surface.

(b(ii))[2]

Treat the sphere as a capacitor. Find its capacitance.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Electric field strength is equal to the potential gradient” …

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