Applied Electricity 1 , May/June 2009

Applied Electricity 1 , May/June 2010

Questions:		1	2		Main

General Comments
Weakness/Remedies
Strength

Question 1

AIM: The aim of both experiments is to investigate the voltage drops across each branch in the circuit.

(a) Connect the circuit as shown in Fig.l.
(b) Ask the Supervisor to check the circuit.
(c) Copy Table 1.

	Vl(v)	V2(v)	V3(v)
Voltmeter
reading

(d) Close the switches 51 and 52'
(e) Measure, read and record in Table 1 the voltage drop across Ri•
(f) Repeat step (e) for R2 and R3•
(g) Evaluate Ei + Vi'
(h) Evaluate E2 + V2•
(i) Compare the values obtained in steps (g) and (h) with V3.
(j) What is the conclusion?
(k) Evaluate:
(i) VdRi;
(ii) V2/R2;
(iii) V3/R3
(I) Comment on your results in (k).

_____________________________________________________________________________________________________

Observation

The candidates were required to
(i) connect the circuit as shown and take voltmeter readings;
(ii) evaluate the voltage drops across each branch in the circuit;
(iii) evaluate the current flowing in each branch of the circuit;
(iv) make a comment on the currents in the circuit.

The expected answers were:

	V1(v}	Vz(v)	V3(v)
Voltmeter	-3.4	-0.4	8.6
reading

(k)
(i) VdR1 =-3.429/10 = -0.3429 A
(ii) Vz/Rz =-0.429/5 = -0.0858 A
(iii) V3/R3 = 8.571/20 = 0.4286 A

(I) The addition of 11 and 12 gives 13 irrespective of the polarity

The candidates understood the task, connected the circuit and obtained readings with a good number obtaining accurate readings, performing the required calculations. However, some did not obtain accurate readings, even though they performed the calculations, their results were incorrect.
Their inability to obtain accurate readings impacted negatively on their performance