Physics Paper 2, Nov/Dec. 2011  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Main
General Comments

Question 9

 Explain briefly the principle of action of a discharge tube.


 This question was poorly attempted by the few candidates that attempted it.  Many of them described the discharge tube instead of explaining its working principle.

The expected answer is:

 The pressure of air/gas in the closed tube is reduced using a (vacuum) pump.  A (very)high voltage is applied across the electrodes.  The remaining air/gas at (very)  low pressure conducts giving rise to a discharge  (between the electrodes).


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