The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below – I ( amperes ) 0 . 5 1 . 0 2 . 0 3 . 0 4 . 0 V ( volts ) 1 . 6 3 . 4 6 . 7 10 . 2 13 . 2 Plot a graph between V and I and calculate the resistance of that resistor.

From Ohm's law, V = I R ⇒ I = V R Thus, the slope of graph I vs V gives 1 R . ⇒ 1 R = 3 . 0 - 1 . 0 10 . 2 - 3 . 4 = 2 . 0 6 . 8 ⇒ R = 3 . 4 Ω

Two lamps, one rated 100 W at 220 V , and the other 60 W at 220 V , are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is 220 V ?

Given, Rated power of first bulb, P 1 = 100 W and Rated voltage, V = 220 V Rated power of second bulb, P 2 = 60 W and Rated voltage, V = 220 V Resistance of the first lamp , R 1 = V 2 P 1 = 220 2 100 = 484 Ω Resistance of the second lamp, R 2 = V 2 P 2 = 220 2 60 = 806 . 67 Ω If these two resistors are joined in parallel, equivalent resistance, R e q = 484 × 806 . 67 484 + 806 . 67 Current drawn from the line , I = V R e q ⇒ I = 220 484 × 806 . 67 484 + 806 . 67 = 220 302 . 5 = 0 . 727 A

How much energy is given to each coulomb of charge passing through a 6 V battery?

The potential difference created by battery, ∆ V = 6 V The potential difference between two points in a circuit is defined as the energy required (or work done) in moving one coulomb of charge from one point to the other. ∆ V = W q , where W is work done by battery and q is the charge. ⇒ W = Δ V × q = 6 V × 1 C = 6 J

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What determines the rate at which energy is delivered by a current?

Important Questions on Electricity

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 1

A piece of wire of resistance

R

is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is

R'

, then the ratio

\frac{R}{R'}

is –

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 2

Which of the following terms does not represent electrical power in a circuit?

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 3

An electric bulb is rated

220 V

and

100 W

. When it is operated on

110 V

, the power consumed will be –

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 4

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 5

How is a voltmeter connected in the circuit to measure the potential difference between two points?

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 6

A copper wire has a diameter

0.5 mm

and resistivity of

1.6 \times 10^{- 8} Ω m

. What will be the length of this wire to make its resistance

10 Ω

? How much does the resistance change if the diameter is doubled?

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 7

The values of current $I$ flowing in a given resistor for the corresponding values of potential difference $V$ across the resistor are given below –

$I (amperes)$	$0.5$	$1.0$	$2.0$	$3.0$	$4.0$
$V (volts)$	$1.6$	$3.4$	$6.7$	$10.2$	$13.2$

Plot a graph between $V$ and $I$ and calculate the resistance of that resistor.

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SCIENCE TEXTBOOK FOR CLASS X>Chapter 12 - Electricity>EXERCISES>Q 8

When a $12 V$ battery is connected across an unknown resistor, there is a current of $2.5 mA$ in the circuit. Find the value of the resistance of the resistor.

What determines the rate at which energy is delivered by a current?

Important Questions on Electricity

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