Part (a): This was not a popular question among the candidates probably due to the fact that most schools could not afford to two sets of resistance boxes for each set-up. However, the few responding candidates performed averagely. The determination of y = was not correctly evaluated.

Part (b): Many candidates gave good responses.

In part (a), candidates are expected to:

- Measure and record
*Emf* of battery to at least 1 d.p in volts.
- Measure and record
**Vo** to at least 1 d.p in volts.
- Record
**five** values of **R** in ohms.
- Read and record
**five** values of **V**1 to at least 1 d.p in volts and in trend.

(Trend: As **R** increases, **V***1* decreases)

- Show composite table containing
**R, V1** and **V1-1**

- Plot a graph using reasonable scales
- Draw line of best fit
- Determine the slope of the graph
- Evaluate y =

State any **two** of the following precautions:

e.g - Key removed when not taking readings

- Ensured tight/clean terminal

- Avoided parallax error in reading voltmeter

- Noted and corrected/avoided zero error on the voltmeter

- Repeated readings shown on table.

In part (b), the expected answers are:

(i) The potential difference (in volts) between two points in a circuit is the

work done (in joules) when one unit of positive charge (coulomb) moves from

one point to the other

E = IR + Ir

3 = 0.5 x 4 + 0.5r

3 = 2 + 0.5r

r = __3 - 2__

0.5

= 2Ω