Basic Electronics Paper 2, WASSCE (SC), 2021

Question 1

 

  1.  Define the following:
  1. mutual inductance;
  2. self inductance.

 

  1.  Figure 1 is an inductive circuit.


Calculate the:

  1. effective inductance;
  2. inductive reactance of the circuit.

 

Observation

      The expected responses were:

  1. (i)        Mutual Inductance may be defined as that property of inductors through which

emf is induced in one coil as a result of changes in the flux linkage due to changes in current in an adjacent coil. It is a measure of the ability of a coil to oppose changes in current in an adjacent coil.

(ii)Self-inductance may be defined as that property of the coil that determines the emf induced in the coil when magnetic flux linking with it changes with time.

 

  1.   (i)       The equivalent inductance of the 0.6H inductors connected in parallel is

                                                                                                         
Therefore the equivalent inductance of all 4 inductors is
                                                                                                
(ii)      The circuit’s effective inductive reactance is
              
                                          
Question 1 required candidates to define the different types of inductance in the first task and calculate effective inductance and inductive reactance of an inductive circuit. The Chief Examiner reported that a good number of the candidates responded well the tasks but the definition of mutual inductance.