Page 47 - CHAPTER-1 (Electricity)
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CHAPTER 1
ELECTRICITY
KEY POINTS
q
• Electriccurrent= Chargeflowing =
Timetaken t
1
• The resistance of a conductor can be given by the expression R=ρ
A
• The total resistance in series circuit (R ) is given by R = R + R + R
2
3
1
s
s
+ .......
• The total resistance in parallel circuit (R ) is given by
p
1 = 1 + 1 + 1 +.....
R p R 1 R 2 R 3
• Joule’s law of heating tells us that the amount of heat produced in
a conductor is directly proportional to the
(i) square of the current flowing through the given conductor.
(ii) the resistance of the conductor and
(iii) time for which the current is passed.
2
2
• Electric power, P = VI = I R = V /R watt.
2
2
• Electric energy = VIt = Pt = I Rt = V t/R J
• Commercial unit of electric energy.
6
1 kWh = 1000 Wh = 3.6×10 J
45
