Question 3
AIM: To test candidates’ knowledge of vehicle lighting circuits.
(a) Connect the circuit as shown in Fig. 3.
(b) Ask the supervisor to check the circuit connect connection.
(c) With switches S1 and S2 open and all lamps in position, observe and record in
Table 3 the state of lamps L1, L2, L3, and L4 as either ON or OFF.
(d) Repeat step (c) for other conditions of the switches and lamps as listed in Table 3.
Table 3
|
Condition of switches and lamps |
L1 |
L2 |
L3 |
L4 |
I. |
S1 open, S2 open and all lamps in position |
|
|
|
|
II. |
S1 closed, S2 open and all lamps in position |
|
|
|
|
III. |
S1 closed, S2 open and lamp L2 removed |
|
R |
|
|
IV. |
S1 closed, S2 open and lamp L3 removed |
|
|
R |
|
V. |
S1 open, S2 closed and all lamps in position |
|
|
|
|
VI. |
S1 open, S2 closed and lamp L1 removed |
R |
|
|
|
VII. |
S1 open, S2 closed and lamp L4 removed |
|
|
|
R |
VIII. |
S1 closed, S2 closed and all lamps in position |
|
|
|
|
IX. |
S1 closed, S2 closed and lamps L1 and L2 removed |
R |
R |
|
|
X. |
S1 closed, S2 closed and lamps L1 and L4 removed |
R |
|
|
R |
[Hint: R indicates that lamp is removed]
(e) State:
(i) the type of circuit connection in Fig. 3;
(ii) two types of vehicle lights where the connection in Fig. 3 is employed;
(iii) the function of the fuse in the circuit.
(f) State two precautions taken in carrying out the experiment.
Observation
Table 3
|
Condition of switches and lamps |
L1 |
L2 |
L3 |
L4 |
I. |
S1 open, S2 open and all lamps in position |
OFF |
OFF |
OFF |
OFF |
II. |
S1 closed, S2 open and all lamps in position |
ON |
OFF |
OFF |
ON |
III. |
S1 closed, S2 open and lamp L2 removed |
ON |
R |
OFF |
ON |
IV. |
S1 closed, S2 open and lamp L3 removed |
ON |
OFF |
R |
ON |
V. |
S1 open, S2 closed and all lamps in position |
OFF |
ON |
ON |
OFF |
VI. |
S1 open, S2 closed and lamp L1 removed |
R |
ON |
ON |
OFF |
VII. |
S1 open, S2 closed and lamp L4 removed |
OFF |
ON |
ON |
R |
VIII. |
S1 closed, S2 closed and all lamps in position |
ON |
ON |
ON |
ON |
IX. |
S1 closed, S2 closed and lamps L1 and L2 removed |
R |
R |
ON |
ON |
X. |
S1 closed, S2 closed and lamps L1 and L4 removed |
R |
ON |
ON |
R |
(e)
(i) Parallel connection
(ii) Types of vehicle light where the connection is employed
- Brake light
- Headlight
- Reverse light
- Park light
(iii) Function of the fuse in the circuit
To protect the circuit against surge/high current.
(f) Precautions in carrying out the experiment
- Ensure tight connection
- Ensure the correct polarity of battery
- Avoid short circuiting.
Question 3 required candidates to connect a circuit with the provided diagram, follow a series of switching instructions and observe the lamps that were either ON or OFF at any instance. Only a few candidates attempted Question 3 and majority of them responded fairly well.