Electricity Worksheet-12
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An electric kettle is rated at 230 V, 1000 W. What is the resistance of its element ? What maximum current can pass through its element?
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Two bulbs A and B are rated 100 W – 120 V and 10 W - 120 V respectively. They are connected in parallel across a 120 V source. Find the current in each bulb. Which bulb will consume more energy?
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What does an electric circuit mean ?
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Define the unit of current.
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Calculate the number of electrons constituting one coulomb of charge.
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Name a device that helps to maintain a potential difference across a conductor.
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What is meant by saying that the potential difference between two points is 1 V ?
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How much energy is given to each coulomb of charge passing through a 6 V battery ?
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On what factors does the resistance of a conductor depend?
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Will current flow more easily through a thick wire or a thin wire of the same material when connected to the same source ? Why ?
Answer:
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As
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Resistance of bulb A, i.e.,
Resistance of bulb B, i.e.,
Current through bulb A, i.e.,
Current through bulb B, i.e.,
Bulb A will consume more energy than the bulb A when these are connected in parallel.
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An electric circuit is a closed and continuous path through which an electric current flows.
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The SI unit of current is called an ampere (A). Current flowing through a conductor 1 ampere if 1 coulomb of charge flows through it in 1 second, i.e.,
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The charge on an electron, e = 1.6 × 10–19 C. Number of electrons constituting 1 coulomb is :
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A battery (consisting of one or more electric cells) is used to maintain a potential difference across a conductor.
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Potential difference between two points in a current-carrying conductor is 1 volt if 1 joule of work is done to carry a charge of 1 coulomb from one point to the other, i.e.,
or
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W = QV = 1C × 6V = 6J.
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The resistance (R) of a conductor depends upon :
(i) its length (l) where R ∝ l.
(ii) its cross-sectional area (A) where R ∝ 1/A.
(iii) resistivity (p) of its material where R ∝ p. Thus, R = p l/A.
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The current flows more easily through a thick wire than through a thin wire. This is due to the reason that the resistance R of a thick wire is less than that of a thin wire R ∝ 1/A. Thick wire has large cross section than thin wire.