Auto Electrical Works Paper 3, WASSCE (SC), 2017

Question 1

 

AIM: To determine the characteristics of a simple cell.

 

 


  1. Connect the circuit as shown in Fig. 1.
  2. Ask the supervisor to check the circuit connection.
  3. Insert lamps L1, L2, L3 and L4 into the circuit.
  4. Close switch Sand record the state of the lamps in the spaces provided.
  5. Measure and record in Table 1 the voltage drop across lamps L1, L2, L3 and L4.
  6. Comment on the result in step (e).
  7. Measure and record in Table 1 the current flowing through lamps L1, L2, L3 and L4.
  8. Comment on the result in step (g).
  9. Open switch S.
  10. State two applications of this type of circuit in a motor vehicle.
  11. State two precautions taken in carrying out the experiment.

 

                                                     Table 1


Lamp

Voltage drop (V)

Current (A)

L1

 

 

L2

 

 

L3

 

 

L4

 

 

 

 

Observation

 

The expected answers were

  • Correct circuit connection                                                                                   

(d) Lamps L1,L2,L3 and L4 are ON/glow light                                                           
(e) In Table 1
(f) The voltages dropped across the lamps are equal                                                 
(g) In Table 1
(h) The current is equally divided through the lamps.        

                                       
                                       Table 1


Lamp

Voltage drop (V)

Current (A)

L1

10 – 12

1.67 – 2.00

L2

10 – 12

1.67 – 2.00

L3

10 – 12

1.67 – 2.00

L4

10 – 12

1.67 – 2.00

 

(j) Applications of circuit in motor vehicle

  • Head light
  • Tail light
  • Indicator light
  • Brake light

     (k) Precautions in carrying out the experiment

  • I ensured tight connections
  • I avoided error due to parallax in meter readings
  • I avoided short circuit

Majority of the candidates that attempted this question responded well. Only a few students did not show they understood what was required of them.