waecE-LEARNING
Home
Technical
Mathematics
Languages
Science
Social Science
Art
Literature Arabic Islamic Studies C.R.K HistoryMusicVisual Art Clothing/Textile Home Management Shorthand
 
Electronics Paper 2, May/June 2009  
Questions: 1 2 3 4 5, 6 &7 8 9 10 Main
General Comments
Weakness/Remedies
Strength
















Question 3

(a)        Figure 7 is a transistor a.f. amplifier with a current gain (β) of 100. 
           Calculate the values:
(i)         VCE (max);
(ii)        Ic (sat.).

(b)(i)    Draw the d.c. load line Vce(Q) and Ic(Q)
    (ii)    Show on the d.c. load line in (b) (i) the values for Vce and Ic at Q.

_____________________________________________________________________________________________________
OBSERVATION

The expected answers were:

(a)(i)    VCE(max) is Vcc = 6v
    (ii)   Ic(max)    =  Vcc/RL = 6/2000  =  3mA. 

(b)       The load line specified by the values of VCE(max) and IC(max)  
            obtained above is displayed below.

(c) Candidates should pick any quiescent point on this load line and specify the coordinates.

This question was on the application of RLC circuits.  This question was quite unpopular.  However, the requirements or the solution was very simple - the load-line is a straight line specified by the points here identified as (O, Vcc) on the
                                Rc

vertical axis and (Vcc, O)on the horizontal axis which was suggested could be made simpler.

The Q-point (the transistor’s operating point) could be selected on this line
Powered by Sidmach Technologies(Nigeria) Limited .
Copyright © 2012 The West African Examinations Council. All rights reserved.