Question 3
- Fig. 2 is the cross-sectional view of an ignition coil.
(i) Identify the parts labeled P, Q, R, S and T.
(ii) State the importance of the laminated soft iron core.
(iii) Mention one physical difference between parts S and T.
(iv) Give two symptoms of a faulty ignition coil in the operation of a motor vehicle.
(b) List three other components of the ignition system other than the ignition coil.
The expected responses were:
- (i) Identify the labeled in figure 2
P high tension lead to distributor cap
Q positive terminal/low terminal tension terminal connected to switch
R negative terminal/low tension terminal connected to the contact breaker and
Capacitor
S primary winding
T secondary winding
(ii) Importance of the laminated soft iron core
- prevent short circuiting/prevent losses/increases electromagnetism
(iii) Physical difference between parts S and T in figure 2
- S is thicker than T
- number of turns of S is fewer than T
(iv) Symptoms of a faulty ignition coil in the operation of a motor vehicle
- back firing
- starting problems
- poor fuel economy
- engine misfiring
- vehicle stalling
- Other components of the ignition system other than the ignition coil
- ignition key
- spark plugs
- distributor cap
- battery
- rotor
- distributor unit
- condenser
- contact breaker
- centrifugal mechanism
Question 3 required candidates to show a level of understanding of the ignition coil. The Chief Examiner reported that while only a few candidates responded well to the first task, majority of the candidates that attempted question had an average performance.
The expected responses were:
- (i) Identify the labeled in figure 2
P high tension lead to distributor cap
Q positive terminal/low terminal tension terminal connected to switch
R negative terminal/low tension terminal connected to the contact breaker and
Capacitor
S primary winding
T secondary winding
(ii) Importance of the laminated soft iron core
- prevent short circuiting/prevent losses/increases electromagnetism
(iii) Physical difference between parts S and T in figure 2
- S is thicker than T
- number of turns of S is fewer than T
(iv) Symptoms of a faulty ignition coil in the operation of a motor vehicle
- back firing
- starting problems
- poor fuel economy
- engine misfiring
- vehicle stalling
- Other components of the ignition system other than the ignition coil
- ignition key
- spark plugs
- distributor cap
- battery
- rotor
- distributor unit
- condenser
- contact breaker
- centrifugal mechanism
Question 3 required candidates to show a level of understanding of the ignition coil. The Chief Examiner reported that while only a few candidates responded well to the first task, majority of the candidates that attempted question had an average performance.