Applied Electricity 1 , May/June 2008

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Questions:		1		Main

General Comments
Weakness/Remedies
Strength

Question 1

question 1

Fig 1

Connect the circuit as shown in fig. 1.
Ask the Supervisor to check the circuit.
Copy Table 1.

Switch	Switch	Lamp
A	B
Off	Off
Off	On
On	Off
On	On .

(d)    Set switches A and B to off positions.
(e)    Close the decision switch S permanently.
(f)     Observe and record the behaviour of the lamp.
(g)    With switch A still in off position, set switch B to on position.
(h)    Observe and record the behaviour of the lamp.
(i)     Set switch A to on position and switch B to off position.
(j)      Observe and record the behaviour of the lamp.
(k)    Set both switches A and B to on positions.
(I)     Observe and record the behaviour of the lamp.
(m) Describe the behaviour of the lamp when operating the two switches as instructed.

_____________________________________________________________________________________________________

Observation

These candidates were required to:

connect lamps through switches to a source of power supply (a.c);
Observe and record the behaviour of the lamps as the switches are operated.

The expected answers were:

Switch A	Switch B	Lamp
Off	Off	Off
Off	On	On
On	Off	On
On	On	Off

The lamp will be ON when both switches A and B are either in ON or OFF position.
The lamp will be OFF when any of the switches A and B is either in ON or OFF position.

Candidates displayed the same strength and weakness as in question one. They got and recorded correctly the behaviour of the lamp but were not all able to interpret the ON and OFF behaviour