Auto Electrical Works Paper 3, May/June 2015

Question 1

(a) Connect the circuit as shown in Fig 1.

(b) Copy Table 1 into your answer booklet.  

                                       Table 1


Task

Reading

Battery terminal voltage on load (switch closed)

 

Battery terminal voltage off load (switch opened)

 

Voltage across lamp 1

 

Voltage across lamp 2

 

Voltage across lamp 3

 

Voltage across lamp 4

 

(c) Measure and record in Table 1 the battery terminal voltage when switch S is opened.

(d) Close switch S.

(e) Measure and record in Table 1 the battery terminal when the switch S is closed.

(f) With switch still closed, measure the voltage drop across lamp1, lamp2 lamp3 and lamp 4 and record your readings in Table 1.

(g) Remove lamp 1 and record the state of other lamps.  

Observation

The expected answers were;

(a) Correct copying of the Table in into the answer booklet  

                                   
                                       Table 1


Task

Reading

Battery terminal voltage on load (switch closed)

2V – 14V

Battery terminal voltage off load (switch opened)

10V -12V

Voltage across lamp 1

± 12V

Voltage across lamp 2

± 12V

Voltage across lamp 3

± 12V

Voltage across lamp 4

± 12V

(b) Battery terminal voltage reading when switch is opened (10V – 12V)

(c) Battery terminal voltage reading when switch is closed ( 2V – 14V)

(d) Voltage across each of lamps 1,2,3 and 4 ( ±12V each)

(e) The remaining lamp will still be on.

The candidates were required to determine a battery terminal voltage; no load and on load, voltage across four lamps connected in parallel.

The candidates' performance was reported to be below average in this question.