Auto Electrical Works Paper 2, WASSCE (SC), 2019

Question 6

 

  1. Table 5contains some indicators on a car dashboard.

  2. Table 5

     

    Indicator

    Quantity measured

    Unit of measurement

    (i)

    Speedometer

     

     

    (ii)

    Tachometer

     

     

    (iii)

    Odometer

     

     

                            Complete Table 5.     

  3.  List five warning lights on the dashboard of a motor vehicle.


  4.     
  5. Fig. 4 is the circuit diagram of a motor vehicle horn.

  6. question 
    Highlight in four steps, the principle of operation of the horn, starting from the push of
    the switch.

Observation

  1. The candidates were expected to copy and complete the table.
  2. Table 5

     

    Indicator

    Quantity measured

    Unit of measurement

    (i)

    Speedometer

    Instantaneous speed of vehicle

    Kilometer per hour/
    Mile per hour

    (ii)

    Tachometer

    Rotation speed  of crank shaft/engine

    Revolution per minute (RPM)

    (iii)

    Odometer

    Distance travelled by a vehicle

    Kilometer/Mile

                                                                                                                           
        

  3.     Warning lights on the dashboard of a motor vehicle
    • Seat belt warning light/reminder
    • Engine warning light
    • Tyre pressure warning light
    • Oil pressure warning light
    • Traction control warning light
    • Engine temperature warning light
    • Anti-lock brake warning light
    • Automatic shift lock/engine start indicator
    • Battery alert
    • Fuel indicator symbol
    • Air bag indicator
    • Fog lamp indicator
    • Security light
    • Washer fluid indicator

     

         

  4.    Highlight of the principle of operation of a motor vehicle horn
  • When the switch is pushed, current flows through the coil and the circuit

making the horn to honk

  • The coil becomes an electromagnet and attracts the iron at the contact
  • The contact breaks and the honking stops
  • The make and break is repeated for as long as the switch is pushed.

As reported by Chief Examiner, majority of the candidates that attempted question 6 responded very well to the principle of operation of the horn while responses to other tasks were only fairly good.