Applied Electricity Paper 2 , Nov/Dec. 2014  
Questions:   1 2 3 4 5 6   Main
General Comments

Question 1

⦁ State Ohm’s law.
⦁ Calculate the resistance of a conductor that has a conductance of 20 µS.
(c) An electric heater consumes 2.16 MJ when connected to a 240 V supply for
30 minutes.
(i) power rating of the heater;
(ii) current taken from the supply.




The expected answers were:
1(a) Ohm’s law states that the current I, flowing through a metallic conductor is directly proportional to the potential difference across its ends provided temperature and all other physical factors are kept constant.
V α I or I α V
V = kI where V=voltage, I= current and k is the constant of proportionality

(b) Conductance, in Siemens, G = OR R =
R =
R= 50 kΩ

(c)(i) Power rating of heater, P =
= 1200 J/s = 1.2 kW
(ii) I =
= = 5 A

The question was on Direct Current Circuit Theory. The question was popular with the candidates The performance was reported good.


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