Electronics Paper 2, May/June 2014  
Questions: 1 2 3 4 5 6 7 Main
General Comments

Question 4
  1. Define the following terms:

(i)   magnetic flux density;
(ii)  electric flux density.

  1.  State the units for each quantity in 4(a)(i) and (ii).
  2.  A coil has a flux density of 0.2 T and a cross-sectional area of 4 x 10-4 m2. Calculate the total flux in the core.

 The expected answers were:
(a)(i)    Magnetic flux density

Magnetic lines of force per unit area within a substance through a plane at right angle to the flux

                             (ii)   Electric flux density

The number of electric lines of force passing through a given area.                                                                                                              
                        (b)(i)    Units   -  Weber/m2 or Tesla                                                   

                            (ii)    Units   -  Coulomb/square meter                                            

                                       = 0.2 x 4 x 10-4 = 80 x 10-6 Wb

            The question was on Electric and Magnetic Fields. It was popular with the candidates, however, their performance was reported average

Powered by Sidmach Technologies(Nigeria) Limited .
Copyright © 2015 The West African Examinations Council. All rights reserved.