Electricity Worksheet-23
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State which has a higher resistance : a 50 W or a 25 W lamp bulb and how many times ?
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What is the power of torch bulb rated at 2.5 V and 500 mA ?
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There are two electric bulbs, (i) marked 60 W, 220 V and (ii) marked 100 W ; 220 V. Which one of them has higher resistance ?
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Out of the two, a toaster of 1 kW and an electric heater of 2 kW, which has a greater resistance?
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What is the SI unit of electrical potential ?
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What Is meant by the statement "Potential difference between two points A and B in an electric circuit is 1 volt" ?
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Why is series arrangement not used for connecting domestic electrical appliances in a circuit ?
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Out of 60 W and 40 W lamps, which one has a higher resistance when in use ?
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Draw a schematic diagram of an electric circuit consisting of a battery of two cells, each of 1.5 V; 5 Ω, 10 Ω, 15 Ω resistors and a plug key, all connected in series.
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An electric bulb draws a current of 0.2 A when the voltage is 220 volts. Calculate the amount of charge flowing through it in one hour.
Answer:
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A 25 W lamp has double the resistance of a 50 W lamp.
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V = 2.5 V,
I = 500 mA = 500 × 10–3 A = 5 × 10–1 A,
P = VI = (2.5 V) (5 × 10–1 A) = 1.25 W
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(i)
(ii)
R2 is higher.
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Here; P1 = 1kW, P2 = 2kW
Resistance of the toaster,
Resistance of the electric heater,
or R1 = 2R2, i.e., R1 > 2R2.
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volt (V).
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One joule of work is done to bring one coulomb of charge from point A to point B in an electric field.
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In a series circuit, same current flows through all the electrical appliances. Since different appliances need currents of different values, so it is not advisable to connect these in series.
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We know that resistance of the lamp, or Thus, a 40 W lamp has a higher resistance than a 60 W lamp.
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The schematic diagram of the required circuit is shown in
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Q = It = 0.2 A × 1 hour = 0.2 A × 3600 s = 720 C.