Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

(a)[1]

What is meant by electric field strength?

(b)[8]

A uniform electric field accelerates an electron from point A to point B, as shown in Fig. 3.1. The separation between A and B is $12\,\text{mm}$. The speed of the electron at A is $2.5\,\text{km s}^{-1}$ and at B is $18\,\text{Mm s}^{-1}$. Calculate (i) the acceleration of the electron, (ii) the change in kinetic energy of the electron, (iii) the electric field strength.

(b(i))[2]

Calculate the acceleration of the electron.

(b(ii))[3]

Calculate the change in kinetic energy of the electron.

(b(iii))[3]

Calculate the electric field strength.

(c)[3]

An $\alpha$-particle travels from A to B in the electric field in (b). Describe and explain how the change in the kinetic energy of the $\alpha$-particle compares with that of the electron. Numerical values are not needed.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Force acting on each unit (positive) charge

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