waecE-LEARNING
Basic Electricity Paper 3 , May/June 2014  
Questions:   1 2   Main
General Comments
Weakness/Remedies
Strength





















Question 2

AIM: To determine the equivalent resistance of a circuit.


  1.   Connect the circuit as shown in Fig. 2.
  2.   Ask the Supervisor to check the circuit connection.
  3.   Copy Table 2into your answer booklet.

 

Table 2          

Source voltage, Vs(V)

Ammeter reading (mA)

Voltmeter reading (V)

5

 

 

10

 

 

15

 

 

20

 

 

25

 

 

 

 

 

 

  1.   Close switch S3.
  2.   Adjust the source voltage, Vs to 5V.
  3. Read and record in Table 2 the ammeter and voltmeter readings.
  4. Open switch S3.
  5. Repeat steps (d) to (g) by increasing the source voltage, Vs to 10 V, 15 V,

20 V and 25 V.

  1. Plot a graph of V(V) on the vertical axis against I (mA) on the horizontal axis.
  1.   Determine from the graph, the equivalent resistance of the circuit.
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Observation

The candidates were expected to connect the circuit as shown in Figure2, measure and record the expected ammeter and voltmeter readings. They were also to plot a graph and determine from the graph the equivalent resistance of the circuit.
The expected answers were:
Table 2          

Source voltage, Vs(V)

Ammeter reading (mA)

Voltmeter reading (V)

5

1.12

5

10

2.24

10

15

3.36

15

20

4.48

20

25

5.61

25

                                                                                                           

                       

Candidates did well in this question but for the inaccurate readings. The performance was reported.
It is right to assume that if candidates have enough and accurate apparatus, the accuracy of the readings will improve. Evidence of group work was shown in their readings and this did not bring out the best in the candidates. Group work testifies that candidates did not have enough apparatus to work with. This should be highly discouraged during examination.

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