Applied Electricity 1, Nov/Dec 2011
 Questions: 1 2 Main
Weakness/Remedies
Strength

Question 2

AIM: To study series and parallel combinations of resistors.

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

Table 2

 VAB(V) V1(V) V2(V)

1.   Close switch S.
2.   Set the power supply to 12 V.
3.   Measure the voltage VAB with multimeter and record in Table 2.
4.   Measure V1 and V2 with the multimeter and record in Table 2.
5.   Evaluate V1 + V2.
6.   Compare step(f) with step(h).
7.   Open switch S.

1.   Connect a third resistor R3 in parallel with the resistor R1 as shown in Fig. 3.
2.   Copy Table 3 into your answer booklet.

Table 3

 RCD(Ω) I(A)

1. Measure the resistance between points C and D in Fig. 3 and record

in Table 3.

1.      Close switch S.
2.      Read and record the ammeter reading A in Table 3.
3.      Evaluate
4.      Compare step (m) with step (p).

The candidates were expected to connect the circuit as shown in figures 2 and 3, measure and record in Tables 2 and 3 the expected readings. They were also required to evaluate some quantities and do some comparisons.

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Observation

The expected answers were:
(c)                                   Table 2

 VAB(V) 12 V V1(V) 6 V V2(V) 6 V

(h)     V1 + V2 = (6 + 6) V = 12 V
(i)      On comparing step (f) with step (h), the two are the same.
Table 3

 RCD(Ω) 705 Ω I(A) 0.017 A

(p)      =  = 705.88 Ω
(q)     On comparing step (m) with step (p), the measured resistance, RCD is
equal to the calculated value.

Candidates did well in this question. Majority of them obtained accurate reading.