This question was fairly answered by most candidates. However, many failed to get the trend of VL correctly, probably candidates did not make wire into a loop as demanded by the question.
The (b) part was not well attempted.
In part (a) the candidates were expected to:
measure and record to1 decimal place six value of l;
(iii)read and record to 1 decimal place six values of Vi ; (Trend: as l increases,Vi increases then decreases)
(iv)read and record to 1 decimal place six values of VR ;
(v) evaluate six values of ; Vi ;
VR
(vi) record data in a composite table showing Ɩ, VƖ, VR, and Vl / VR ;
(vii) indicate the graph axes, select reasonable scales, plot six points;
(viii) draw a smooth curve through the points;
- show and record the maximum value of M and the corresponding value of l;
(x) state any two of the following precautions in acceptable form:
Ensured tight connections/ clean terminals
- Removed key after each reading
- Avoided parallax error in reading voltmeter
- Evidence of repeated readings
- Noted and corrected for zero error of voltmeter/meter rule.
(b)(i) Effects of heating on the experimental results
- The constantan wire will increase in length (expand) and length of the loop increases. Consequently the value of Ɩ increases.
- The resistance of the wire increases
- To reduce the effect of heating, remove the key immediately after taking each reading