Auto Electrical Works Paper 2, WASSCE (SC), 2022

Question 3

  1. 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.