Basic Electronics Paper 3, WASSCE (PC 2ND), 2018

Question 1

 

AIM: To determine the phase angle in an RL a.c. circuit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Connect the circuit as shown in Fig.1.
  2. Ask the supervisor to check the circuit connection.
  3. You are provided with Table 1.
  4.  

     

  5. Set the power supply unit to 12 V.
  6. Close switch (S).
  7. Read and record in Table 1 the values of VRC, VCE and VE.
  8. Open switch (S).
  9. Repeat steps (e) to (g) for the other values of supply voltages (VCC) in Table 1.
  10. Complete Table 1.
  11. Comment on your result and state the function of resistor (R1):

Observation

The expected responses were:

 

                           

Comment on result

VT is approximately equal to VCC.

       

Function of resistor R1

    • To bias the base of the transistor.
    • To set the operating point/condition of the transistor.
       

    Chief Examiner reported that candidates responded very well to question 1.