Auto Electrical Works Paper 3, May/June 2015

Question 2

(a) Connect the circuit as shown in Fig. 2.

(b) Copy Table 2 into your answer booklet.  

                                     Table 2


Task

Reading

Battery voltage on load (switch closed)

 

Battery voltage off (switch opened)

 

Voltage across lamp 1

 

Voltage across lamp 2

 

Voltage across lamp 3

 

Voltage across lamp 4

 

(c) Measure and record in Table 2 the battery terminal voltage when switch S is opened

(d) Close switch S.

(e) Measure and record the in Table 2 the battery terminal voltage when switch S is closed.

(f) With the switch still closed, measure the voltage drop across lamp 1, lamp 2, lamp 3 and lamp 4 and record your readings in Table 2.

(g) Remove lamp 2 and record the state of other lamps

(h) Why is it that connecting two or more lamps in series is not desirable in auto circuitry?  

Observation

The expected answers were;

(a) Copying of the Table correctly into the answer booklet  

                                     Table 2


Task

Reading

Battery voltage on load (switch closed)

12V

Battery voltage on load (switch opened)

Between 0V – 12V

Voltage across lamp 1

1V

Voltage across lamp 2

2V

Voltage across lamp 3

3V

Voltage across lamp 4

4V

(b) Battery terminal voltage reading when switch is open (0V – 12V)

(c) battery terminal voltage reading when switch is closed (12V)

(d) voltage across each lamp ( lamp 1=1V, lamp 2 =2V, lamp 3=3V, and lamp 4=4V)

(e) The remaining lamps will go off

(f) Because when one of the lamp blows, the rest will go off

The candidates were required to determine the terminal voltage of a battery on load and no load, voltage drop across four lamps connected in series.

The performance was reported to be averagely good.