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Applied Electricity Paper 2 , May/June 2008  
Questions:   1 2 3 4 5 6   Main
General Comments
Weakness/Remedies
Strength





















Question 1

State two conditions under which resonance will occur in a series RLC circuit.
 (b) A coil of resistance 10Ω and inductance 0.1 H is connected in series with an 80 µFcapacitor. If the supply voltage is 200 V, calculate:
(i)            series resonance frequency;
(ii)           current at this frequency.

_____________________________________________________________________________________________________
Observation

The expected answers were:

  1. (i)  When R = Z
  2. When XL  =  XC
  3. When current is maximum.                                                                        
  4. Fr = 1/(2πѴLC)

 
  = 1/ (2π x Ѵ0.1*80*10-6)

  = 1000/2πѴ8 = 103/2πѴ8

Fr= 56.3 Hz

  1. I = V/R

 = 200/10
I = 20A
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