The candidates were required to

(i) connect a circuit as shown in the diagram above:

(ii) measure five values of lx and ly for wire A to at least 1 decimal place

in trend. Trend: as L decreases, lx increases.

(iii) measure five values of lx and ly for wire B to at least 1 decimal place and

in trend. Trend: as L decreases, lx increases.

(iv) evaluate five values of R1 and R2 correct to 2 decimal places.

(v) present data on a composite and complete table showing L, lx, (A), lY (A), lx

(B), lY B, R1 , R2.

(vi) correctly distinguish the graph axes, select reasonable scales, plot the five

points correctly and draw a line of best fit into the points;

(viii) draw a large right angled triangle on the graph line, read ∆R2 and ∆R,

and evaluate slope = __∆R__²

∆R¹

(ix) Evaluate k = √s.

(x) State any **two** of the following precautions in acceptable form of speech:

- Key removed when not taking readings:

- Ensured tight connections/clean terminals;

- Avoided parallax errors in reading meter rule;

- Jockey not allowed to scratch resistance wire;

- Zero error of metre rule noted and corrected;

b (i) Any two correct advantages potentiometer over the voltmetre e.g

- High accuracy

- Null deflection (does not draw current at balance point)

- Range can be increased as required

- No friction in moving parts.

(ii)The internal resistance of a cell is the opposition to the current flow through [the electrolyte of] the cell.

This question was very popular and well attempted by many candidates. Some candidates however had difficulty in making deductions from the graph. Some failed to record initial ammeter readings as demanded by the question.

Part b was fairly attempted.