Observation

           
Part (a) This was a popular question among the candidates. Many candidates attempted the question and performed well.
(b) Candidates response was fair.
Candidates were expected to:

• measure and record the value of XY to at least 1 d.p in cm.
• read and record the values of Io to at least 1 d.p in A
• read and record the values of Vo to at least 3 d.p in volt
• record six values of R in ohms
• read and record six values of I to at least 1 d.p. in A and in trend
• read and record six values of V to at least 1 d.p. in V and in trend
• show composite table containing at least R, V and I          
• Both axes correctly distinguished   
• plot a graph using reasonable scales
• draw line of best fit
• determine the slope of the graph
• state any two of the following precautions.

e.g.

• Ensured clean terminals.
• Ensured tight connections.
• Key removed when readings were not taken 
• Avoided error of parallax when reading ammeter/voltmeter
• Noted/Avoided zero error when reading ammeter/voltmeter
• Repeated readings shown on table.

b(i)      Ohm’s law                                                                                                 

Provided the temperature is constant, the current passing through a metallic conductor (wire) is directly proportional to the potential difference across its ends