VELAMMAL VIDYALAYA-ANNEXURE-CHENNAI -95

CLASS-10-PHYSICS - CHAPTER-ELECTRICITY
QUESTION BANK
Section -A
1. A charge of 100 C flows through a bulb in 5 minutes. How much current
is flowing through the bulb?
a.500A b.100A c.20A d.0.3 A
2. A metal wire of resistance 12 Ω is bent to form a square. The resistance
between the3 two diagonal points would be ________
a. 12 Ω b. 24 Ω c.3 Ω d.6 Ω
3. A fuse wire is a wire of _______
A .low resistance and low melting point b. high resistance and low
melting point
4. Which material is used to make the filament of the bulb?
a/Copper b.Aluminium c. Silver d.Tungsten
5.The resistivity does not change if_______
a.the material is changed b.the temperature is changed
c.the shape of the resistor is changed d.both material and temperature are
changed.
6.An electric iron draws a current 4A when connected to 220V mains. Its
resistance must be _________
a.1000 Ω b.55 Ω c.44 Ω d.10 Ω
7. A piece of wire of resistance R is cut into five equal parts. These parts are
then connected in parallel, if equivalent resistance of this combination is R1
then the ratio R/R1is ______
a. 1/25 b. 1/5 c.5 d.25
8. Which of the following terms does not represent electrical power in a
circuit?
a. I2R b. IR2 c.VI d.V2/R
9. An electric bulb is rated 220V and 100W. When it is operated on 110V,
the power consumed will be _________
a. 100W b. 75W c.50W d.25W

1|Page Prepared by : Ramalakshmi.U

10. Two conducting wires of the same material and of equal lengths and
equal diameters are first connected in series and then in a circuit across the
same potential difference. The ratio of heat produced in series and parallel
combination would be ____________
a. 1:2 b. 2:1 c.1:4 d.4:1
11. In an electrical circuit two resistors 2 Ω and 4 Ω respectively are
connected in series to a 6V battery. The heat dissipated by the 4 Ω resistor
in 5s will be _________
a. 5J b. 10J c. 20J d. 30J
12. A student carries out an experiment and plots the V – 1 graph of three
samples of nichrome wire with resistance R1, R2 and , R3 respectively. Which
of the following is true?
a. R1=R2=R3
b. R1> R2 > R3
c. R3 > R2 > R3
d.R2>R3>R1
13. A cell, a resistor, a key and ammeter are arranged as show in circuit
diagrams

The current recorded in the ammeter will be ________

a. maximum in (i) b. maximum in (ii)
c.maximum in (iii) d. same in all three circuits.
14. Electrical resistivity of a given metallic wire depends upon ____
a. its length b. its thickness
c. its shape d. nature of the material
15. Unit of electric power may also be expressed as ______
a. volt ampere b. kilowatt hour c.watt second d.joule/ second
16. The physical quantity that determines the rate at which energy is
delivered by __________
a.electric resistance b.potential difference c.electric power

2|Page Prepared by : Ramalakshmi.U

d.electric resistivity
Q.No:17 to 20 are very short answer questions. These consist of two
statements – Assertion (A) and Reason ®. Answer these questions selecting
the appropriate option given below:
a. Both A and R are true and R is correct explanation of A
b. Both A and R are true and R is not the correct explanation of A
c. A is true but R is false
d. A is false but R is true
17. Assertion (A): Tungsten metal is used for making filament of
incandescent lamp.
Reason (R ) The melting point of tungsten is very low.
18. Assertion (A) If a graph is plotted between the potential difference and
the current flowing, the graph is a straight line passing through the origin.
Reason (R ) Based on Ohm’s law the current is directly proportional to the
potential difference.
19. Assertion (A) Alloys are commonly used in electrical heting devids, like
electric iron, toasters etc.,
Reason (R ) Alloys do not oxidise (burn) readily at high temperatures.
20. Assertion (A): A cell is a device which convert che3mical energy into
electrical energy.
Reason (R ): Cell maintains a constant potential difference between its
terminals for a long time.
Section B
21.(a) What is (i) the highest ,(ii) the lowest total resistance that can be
secured by combination of four coils of resistance 4Ω,8Ω,12Ω,and 24Ω?
(b) Write any two advantages of connecting electrical devices in parallel with
the battery instead of connecting them in series?
22.Why does the cord of an electric heater not glow while the heating
element does?
23.(i) Should the resistance of an ammeter be low or high?
(ii) How does the use of a fuse wire protect electrical appliances?
24. What would be the reading of an
ammeter and voltmeter in the given circuit?

3|Page Prepared by : Ramalakshmi.U

25.(a)Why is an ammeter likely to burn out if it is connected in parallel?
(b) Out of two electric bulbs of 50W-220V and100W-220V ,which one will
glow brighter when they are connected in (i)series (ii)Parallel
26.What is the commercial unit of electrical energy ? Represent in joules.
Section C
27. How will you join three resistors ,each of resistance 9 Ω so that the
equivalent resistance of the combination is (i)13.5 Ω (ii)6 Ω
28.With the help of a suitable circuit diagram prove that the reciprocal of
the equivalent resistance of a group of resistances joined in parallel is equal
to the sum of the reciprocals of the individual resistances.
29.(a) Define electric power .An electrical device of resistance R is connected
across a source of voltage V and draws a current I. Derive an expression for
power in terms of current and resistance .
(b) Two electric bulbs rated 100W ,220V and 60W ,220V are connected in
parallel to an electric mains of 220V .Find the current drawn by the bulbs
from the mains.
30.A piece of wire of resistance 20 Ω is drawn out so that its length is
increased to twice its original length .Calculate the resistance of the wire in
the new situation.
31.(i) What is the function of a galvanometer in a circuit?
(ii) Name and define the S.I unit of current .
(iii) Write the function of voltmeter in an electric circuit
32. (a) A 4 Ω resistance wire is doubled on it .Calculate the new resistance of
the wire.
(b) An electric iron consumes energy at a rate of 840 W when heating is at
the maximum rate and 360W when the heating at the minimum .The
applied voltage is 220 V ,What is the value of current and the resistance in
each case ?
33.Five resistances are connected in the shape of letter
A as shown in the figure. Determine the total
resistance of the circuit.
Section D
34.(a) (i)What is electrical resistivity ? Derive its S.I. unit .In a series
electrical circuit comprising a resistor made up of a metallic wire ,the
ammeter reads 100mA.If the length of the wire is doubled ,how will the
current in the circuit change ? Justify your answer.

4|Page Prepared by : Ramalakshmi.U

(ii) List the factors on which the resistance of a conductor in the shape of a
wire depends .
(iii)Why are metals good conductors of electricity ,whereas glass is a bad
conductor of electricity ?
(b) (i) How will you infer with the help an experiment that the same current
flows through every part of the circuit containing three resistors R1,R2,R3 in
series connected to a battery of V volts.?
(ii) In an electric circuit two resistors of 12 Ω each are joined in parallel to a
6V battery. Find the current drawn from the battery .
35. (a) (i) What is meant by resistance of a conductor ? Name and define its
S.I unit. How is the resistance of a wire affected ,if (i) its length is doubled
,(ii)its radius is doubled ?
(ii) A copper wire of resistivity 1.63 x 10 -8 Ωm, has cross section area of
10.3 x 10-4cm2. Calculate the length of the wire required to make a 20 Ω
coil.
(b) (i) Heating element of electrical heating devices is made up of an alloy
rather than a pure metal gives two reasons .
(ii)Four resistances of 4 Ω each are joined end to end to form a square.
Calculate equivalent resistance of the combination between two adjacent
corners?
36.(i) A geyser is rated 1500W ,250 V .It is connected to 250V mains
,calculate (a) the current drawn (b) the energy consumed in 50 hours.(c) the
cost of energy consumed at 2.20perKWh.
(ii) A hot plate of an electric oven connected to a 220V line has two
resistance coil A and B ,each of 24 Ω resistance ,which may be used
separately ,in series or in parallel ,what are the current in the three cases?
Section E
37.A fuse is a device for the safety of appliances and electric circuits against
excessive heating during a short circuit or overloading .It has low melting
point wire connected to live wire .Electric fuse wire is a mixture (alloy) of tin
(Sn)and lead (Pb)(Sn 63% and Pb 37% ).It has high resistance and low
melting point ,so that it may easily melt on over heating when excessive
current is passed through it .The maximum amount of current that can
pass through a fuse wire without melting is called rating of a fuse.
(i) Which device is used to protect an electric circuit from excess current ?
(ii) Define current rating of fuse .
(iii)(a) A room heater rating 1000watt ,220V calculate the current rating of
fuse wire used.

5|Page Prepared by : Ramalakshmi.U

(b) Name the two metals with which fuse wire is made up of .
38.Study the circuit shown below ,in which
three identical bulbs ,B1,B2,and B3 are connected
in parallel with a battery of 4.5V.

(i) What will happen to the other two bulbs if the bulb B3 gets fused?
(ii) The current flowing through B1,B2,and B3 are same .Justify the
statement.
(iii)(a)If the wattage of each bulb is 1.5W,how much reading will the ammeter
A show when all the three bulbs glow simultaneously.
(b)Find the total resistance of the circuit.
39.Ohm’s Law is perhaps the most popularly known of all the laws ,theories
and principles of electrical sciences .The law forms the starting point in the
study of electrical networks and it has reserved ,forever ,a place of honor for
Georg Simon Ohm(1789-1854)in the history of science .The year 1976
marked 150th anniversary of Ohm’s law .From Ohm’s law states I = V/R
Ohm initially called the constant of proportionality R ‘reduced length ‘,but
renamed it as “resistance” shortly thereafter .Ohm obtained this result both
experimentally and theoretically .
(i) In the following circuit ,how much current
would flow through 10ohm resistor and 15 ohm
resistor?
(ii)V-I graphs are drawn individually for two resistors
and their series combination .Out of A, B, C
which one represents the graph for series combination
of the other two? Give reason.

(iii)(a)You have four resistors of 8 Ωeach .Show how would you connect these
resistors to have effective resistance of 8 Ω.?
(b) Find the value of current I in the circuit given as below;

6|Page Prepared by : Ramalakshmi.U