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FIRST SEMESTER 2016-2017
GRADE : X
PHYSICS WORKSHEET -1 (ELECTRICITY )
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1. What length of a copper wire of cross-sectional area 0.01 mm2 would be required to
obtain a resistance of 1kΩ? Resistivity of Cu = 1.7 X 10-8 Ω m. ( Ans : 588.2 m )
2. A metal wire of specific resistance 64 X 10-6 Ω m and length 1.98 cm has a resistance of
7Ω. Find its radius.
( Ans : 0.024 cm )
3. Calculate the resistance of a 2m long nichrome wire of radius 0.321 mm. Resistivity of
nichrome is 15 x 10-6 Ω m .If a P.D of 10 V is applied across this wire, what will be the
current in the wire?
( Ans : 9.26 Ω , 1.08 A )
4. A wire of resistance 10 Ω is drawn out so that its length is thrice its original length.
Calculate its new resistance.
( Ans : 90 Ω )
5. A copper wire has a diameter 0.5 mm and resistivity 1.6x10-8 Ω meter. What will be the
length of the wire to make the resistance 12 Ω? How much will be the resistance of
another copper wire of same length but half the diameter?
(Ans:143.7m, 48 Ω)
6. Draw schematic diagrams of an electric circuit comprising of 3 cells and an electric bulb,
ammeter, plug key in the ON mode and another with same components but with two
bulbs in parallel and a voltmeter across the combination
7. A 9 ohm resistor is cut into three equal parts and connected in parallel. Find the
equivalent resistance of the combination. (ans 1 ohm)
8. Consider the following circuit diagram. If R1=R2=R3=R4=R5=3Ω, find the equivalent
resistance of the circuit. (Ans : 8 ohm)
9. A torch bulb is rated 2.5Vand 750mA. Calculate a) its power, b) its resistance and c) the
energy consumed, if this bulb is lighted for 4 hours.
(Ans : a)1.875W, b)3.33Ω, c)7.5Wh )
10. Five resistors are connected in a circuit as shown. Find the ammeter reading when circuit
is closed. (Ans : 1A)
11. Study the circuit shown in which three identical bulbs B1, B2 and B3 are connected in
parallel with a battery of 4.5V.
i.
ii.
iii.
What will happen to the glow of other 2 bulbs if the bulb B3 gets fused?
If the wattage of each bulb is 1.5W, how much reading will the ammeter A show
when all the three bulbs glow simultaneously? (Ans: 1 Ampere)
Find the total resistance of the circuit. (Ans: 4.5 Ω)
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