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Question : 12
Total: 15
(a) List the factors on which the resistance of a uniform cylindrical conductor of a given material depends.
(b) The resistance of a wire of0.01 cm 10 Ω 50 × 10 − 8 Ω m
OR
(a) What is the meaning of electric power of an electrical? Write its SI unit.
(b) An electric kettle of2 kW 2 h
(i) kilowatt hour and
(ii) joules.
(b) The resistance of a wire of
OR
(a) What is the meaning of electric power of an electrical? Write its SI unit.
(b) An electric kettle of
(i) kilowatt hour and
(ii) joules.
Solution:
(a) Length of conductor, area of its crosssection and its material are the factors on which the resistance of a uniform cylindrical conductor of a given material depends.
(b)
R = 10 ohm ; r = 0.01 cm ;
ρ = 50 × 10 − 8 ohm metre
R = ρ l ∕ A =
10 =
l =
= 0.629 m
OR
(a) Power of electrical device means rate at which electric energy is consumed in an electric circuit. SI unit of power is watt (W).
(b) (i) Energy consumed= W = ×
= 2 kW × 2 h = 4 kWh
(ii)1 kWh = 3.6 × 10 6 J
So, 4 kWh = 4 × 3.6 × 10 6 J = 1.44 × 10 7 J
(b)
OR
(a) Power of electrical device means rate at which electric energy is consumed in an electric circuit. SI unit of power is watt (W).
(b) (i) Energy consumed
(ii)
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