This question on electricity was attempted by many candidates and it was fairly well attempted. Candidates were able to carry out the observation of **d **and** I** in trend to the required decimal places. Plotting of the graph of **I-1** against **d** pose no challenge to most of the responding candidates. Similarly the slope was correctly determined.

Precautions were correctly stated while was correctly evaluated.

In part (b), candidates were able to determine from the graph the value of **I** when **d** = 90 cm but could not determine the value of **R** using intercept **c** on the graph with **E** = 2V.

In part (a) the candidates were expected to:

- Measure and record in cm **six** values of **d** to at least 1 d.p

- Read and record **six** values of **I** in angle to at least 1 d.p and in trend.

- Trend: As **d** increases, **I** decreases.

- Evaluate **I-I** correctly to at least 3 s.f

- Record data in composite table shown at least **d, I **and** I-1**

- Indicate the graph axes, select reasonable scales, plot **six** points and draw line of best fit.

- Determine the intercept on the vertical axis

- Evaluate

- State any **two **of the following precautions in acceptable speech:

- Parallax error was avoided on ammeter

- Key opened when reading was not being taken

- Ensured clean terminals/tight connections

- Zero error noted/corrected on metre rule/ammeter

- Avoided sliding of jockey on the potentiometer wire.

- Repeated readings shown on table.

The expected responses to part (b) are:

Intercept c =

R = c x E

R = 2c

**I-1** corresponding to **d ** = 90 cm correctly shown on graph

**1** correctly evaluated.