Download CURRENT ELECTRICITY MCQ`S

PHYSICS
CHAPTER # 13
Current Electricity
1.
Rate of flow of charge through the surface is known as:
a) Charge
b) Electric current
c) Ampere
d) Coulomb
B
2.
The SI unit of current is:
a) Volt
c) Ampere
C
b) Coulomb
d) None of these
Free electrons are:
a) Loosely bound
c) Fixed
b) Tightly bound
d) None of these
4.
A
5.
In liquids and gases, the current is due to the motion of:
a) Positive charges
b) Negative charges
c) Both positive and negative charges
d) None of these
C
6.
Conventional current (I) is due to the motion of:
a) Flow of positive charge
c) Flow of neutron
A
b) Flow of negative charge
d) None of these
7.
The direction of conventional current in a circuit is:
a) From negative to positive
b) From positive to negative
c) From negative to negative
d) From positive to positive
B
8.
One advantage of conventional direction of current is that current flows from:
a) High potential to low potential
b) Low potential to high potential
c) Negative potential to positive potential
d) None of these
A
9.
The average velocity gained by the electrons in a conductor placed in an electric field is called:
a) Variable velocity
b) Phase velocity
c) Drift velocity
d) Instantaneous velocity
C
10.
Electronic or electric current ‘I’ in a conductor is defined by the relation:
Q
t
a) I =
b) I =
t
Q
c) I = Qt
d) None of these
B
11.
Ampere is a current in which charges flow across any cross-section at the rate of:
a) 2C/S
b) 3 CS-1
-1
c) CS
d) CS-2
C
12.
Current per unit area is called:
a) Current density
c) Potential difference
A
b) Electric charge
d) Resistance
The SI unit of current density is:
a) m2/A
c) m2A
b) A/m2
d) mA2
13.
B
14.
If one ampere current flows through 2m long conductor, the charge flow through this in one hour
will be:
a) 2 C
b) 120 C
c) 3600 C
d) 7200 C
C
15.
The relation V = IR represents:
a) Coulomb’s law
c) Ampere law
B
16.
b) Ohm’s law
d) None of these
“In an electrical circuit, the potential difference across a conductor is directly proportional to the
current flowing through it, provided the temperature of the conductor remains the same”. It is known
as:
a) Ampere’s law
b) Coulomb’s law
c) Ohm’s law
d) None of these
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C
PHYSICS
CHAPTER # 13
Current Electricity
17.
Measure of the opposition to flow of free electrons is knows as:
a) Conductance
b) Charge
c) Current
d) Resistance
D
18.
The SI unit of resistance is:
a) Coulomb
c) Volt
B
b) Ohm
d) Ampere
The graphical representation of Ohm’s law is:
a) Hyperbola
c) Straight line
b) Parabola
d) Ellipse
Ohm is defined as:
a) VA-1
c) AV-1
b) VC-1
d) CV-1
19.
20.
C
A
21.
If potential difference across the conductor is one volt and one ampere current is flowing, then
resistance of the conductor is:
a) One Farad
b) One Ohm
c) One Coulomb
d) One Ampere
B
22.
Resistance of a conductor depends upon:
a) The potential difference between its ends
c) The dimension of conductor
D
b) The nature of material of the conductor
d) All of these
23.
The reciprocal of the resistance of a conductor is called:
a) Specific resistance
b) Current
c) Conductance
d) Effective resistance
C
24.
If the resistance of the conductor is increased then current will:
a) Increase
b) Decrease
c) Remain the same
d) First increase and then decrease
B
25.
When the temperature of a metallic conductor is increased its resistance:
a) Always decreases
b) Always increases
c) May increase or decrease
d) Remains the same
B
26.
If A is area of cross-section of a conductor and L is the length of the conductor, then resistivity “  ”
of a conductor is given by the relation:
RA
L
a)  =
b)  =
L
RA
L A
A
c)  =
d)  =
R
RL
A
27.
The resistance of a conductor of length ‘L’, cross-sectional area ‘A’ and resistivity ‘  ’ is given by:
B
LA


c) R =
AL
a) R =
L
A
L
d) R =
A
b) R =
28.
The resistance of a conductor increases with the increase in its:
a) Cross-sectional area
b) Diameter
c) Length
d) Both diameter and cross-sectional area
C
29.
The resistance of a certain length of wire having diameter 5 mm is 10 Ohms. If diameter is changed
to 10mm, the new resistance will become:
a) 20 Ohms
b) 40 Ohms
c) 5 Ohms
d) 2.5 Ohms
D
30.
Practical unit of resistivity is:
a) Ohm-meter
c) 1  -V
A
b) Ohm-ampere
d) 1  -F
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PHYSICS
CHAPTER # 13
Current Electricity
31.
32.
33.
Reciprocal of resistivity is called:
a) Inductance
c) Conductivity
b) Specific resistance
d) Current
Practical unit of conductivity is:
a) (ohm-m)-1
c) (ohm-V)-1
b) Ohm-m
d) (ohm-A)-1
A
The temperature co-efficient of resistivity is given by the relation:
  PT
a)  = o
PT  T
b)
PT   o
PT  T
d)
c)  =
34.
C
  o
= T
o  T
T  o
o  T
The temperature co-efficient of resistance is given by the relation:
R  RT
R  Ro
a)  = o
b)  = T
RT T
Ro T
c)  =
Ro RT
RT T
d)  =
B
B
RT Ro
RT T
35.
The change in resistivity per unit original resistivity (or resistance) per degree change in temperature
is called:
a) Resistance
b) Conductance
c) Temperature co-efficient of resistivity
d) All of these
C
36.
The SI unit of the temperature co-efficient of resistivity of a material is:
a) Ohm-m
b) K
c) K-1
d) Ohm
C
37.
The resistance of a conductor at absolute zero is:
a) Zero
c) Positive
A
b) Infinite
d) Negative
A good electrical conductor has:
a) Low resistivity and high conductivity
c) No resistivity and no conductivity
b) High resistivity and low conductivity
d) All of these
Resistivity of the typical metal increases:
a) With increase in temperature
c) With constant temperature
b) With decrease in temperature
d) None of these
38.
39.
A
A
40.
The resistivity of a class of elements at critical temperature “T c” falls to zero, such elements (or
materials) are called:
a) Semiconductors
b) Superconductors
c) Conductors
d) Insulators
B
41.
The temperature at which the value of resistivity falls to zero is called:
a) Lowest temperature
b) Zero temperature
c) Critical temperature
d) Absolute zero temperature
C
42.
The phenomenon that the resistance of a metal falls exactly to zero at a few degrees above absolute
zero is called:
a) Conductivity
b) Low conductivity
c) Super-conductivity
d) Low resistivity
C
43.
In a laboratory of Zurich, two scientists Bednorz and Mueller observed that certain ceramic materials
exhibit super-conductivity at much higher temperature, that is at:
a) T = 30 K
b) T = 125 K
c) T = 40 K
d) T = 20 K
A
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PHYSICS
CHAPTER # 13
Current Electricity
44.
New prepared ceramic materials have been found to be super-conductors even at:
a) T = 30K
b) T = 125 K
c) T = 75 K
d) T = 150 K
B
46.
When the resistors are connected in series, then:
a) The total current through each is the same
b) The voltage across each is the same
c) The total resistance is the sum of reciprocals of the individuals
d) The total resistance is the product of the individual resistors
A
47.
If resistors R1, R2, ….. Rn are connected in series, the equivalent resistance Re is given by:
1
1
1
1
1
a)
=
+
+
…..+
b) Re = R1+R2+R3+ ….. Rn
R e R1 R 2 R 3
Rn
c) Re = R1R2R3….. Rn
d) None of these
B
48.
Why should a resistance be introduced in a circuit in series deliberately?
a) To increase current
b) To decrease current
c) To control current
d) None of these
B
49.
Why should different resistance be added in series in a circuit?
a) To increase voltage
b) To decrease voltage
c) To divide voltage
d) None of these
B
50.
When the resistors are connected in series, the equivalent resistance is always:
a) Greater than the greatest resistance in series
b) Less than the largest resistance in series
c) Equal to the greatest resistance in series
d) Less than the smallest resistance in series
A
51.
If resistors R1, R2, ….. Rn are connected in parallel, the equivalent resistance ‘Re’ is given by:
1
1
1
1
1
a)
=
+
+
…..+
b) Re = R1+R2+R3+ ….. Rn
R e R1 R 2 R 3
Rn
A
a) Re =
1
1
1
1
+
+
…..+
R1 R 2 R 3
Rn
b) None of these
52.
In a house circuit, all electrical appliances are connected in parallel to each other between the line an
neutral wires to get:
a) Same current
b) Same current and potential difference
c) Different current but same potential difference d) Different current & different potential diff.
C
53.
When resistors are connected in parallel, the equivalent resistance is always:
a) Greater than the sum of individual resistance
b) Greater than the smallest resistance in the combination
c) Less than the smallest resistance in the combination
d) Equal to the sum of individual resistance
C
54.
Three resistors of resistance 2,3 and 6 Ohms are connected in parallel, their equivalent resistance is:
a) 0.1 ohm
b) 1.0 ohm
c) 3 ohms
d) 2 ohms
B
55.
Three resistors of resistance 2,3 and 6 Ohms are connected in series, their equivalent resistance will
be:
a) 0.1 ohm
b) 1.0 ohm
c) 6 ohms
d) 11 ohms
D
56.
As the charge flows through the conductor energy is dissipated in the form of:
a) Heat
b) Light
c) Solar energy
d) None of these
A
57.
Power dissipated as heat in the conductor of resistance ‘R’ due to electric current ‘I’ is given by:
a) P = I2R2
b) P = I2R
B
c) P =
I2
R
d) P =
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I2
PHYSICS
CHAPTER # 13
Current Electricity
58.
Power dissipated in the form of ‘V’ and ‘I’ can be defined as:
a) P = VI
c) P =
59.
60.
A
V
b) P =
I
I2
d) P = 2
V
V2
I2
Power dissipated in the form of ‘V’ and ‘R’ can be determined as:
V
a) P =
I
V
c) P = 2
R
V2
b) P =
R
V2
d) P =
I
Unit of power, Joule/second is called:
a) Joule
c) Watt
b) Volt
d) Newton
B
C
61.
If one ampere current flows through a resistor against potential difference of one volt, this is called:
a) Ampere
b) Watt
c) Volt
d) Joule
B
62.
Watt is equal to:
a) Joule-coulomb
c) Joule/second
C
b) Joule-second
d) None of these
The practical unit of power is:
a) Watt
c) Joule
b) Kilowatt
d) None of these
One kilowatt is equal to:
a) 103 watts
c) 1012 watts
b) 106 watts
d) None of these
Heat energy dissipated in resistors is defined as:
a) VIt
c) Both a & b
b) I2Rt
d) Neither a nor b
The unit of electrical energy is:
a) Kilowatt-hour
c) Joule
b) Kilowatt
d) None of these
63.
64.
65.
66.
B
A
C
A
67.
Amount of energy delivered by the current in one hour when it supplies energy at the rate of 1000 J/s
is known as:
a) Joule
b) Kwh
c) Newton
d) None of these
B
68.
1 Kwh = _______:
a) 3.6  106 J
c) 6.3  106 J
A
70.
A 1000 watt heater operates on a 220 volt line for one hour. The current passing through heater is:
a) 15 A
b) 7 A
c) 5.4 A
d) 4.5 A
D
72.
A 100 watt bulb is operated by 200 volt, the current flowing through the bulb is:
a) 1 ampere
b) 0.5 ampere
c) Zero ampere
d) 2 amperes
B
73.
The resistance of 60 watt bulb in a 120 volt line is:
a) 30 ohms
c) 240 ohms
C
b) 3.6  108 J
d) 6.3  108 J
b) 120 ohms
d) 60 ohms
YASIR MUKHTAR
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PHYSICS
CHAPTER # 13
Current Electricity
74.
The devices which can maintain a potential difference between points to which they are attached are
known as:
a) Source of electricity
b) Source of electromotive force (emf)
c) Source of heat
d) None of these
B
75.
The work per unit charge done by the source of emf in moving a charge around a closed loop is
called:
a) Electromotive force (emf)
b) Potential difference
c) Potential energy
d) Kinetic energy
A
76.
The total energy expended per coulomb of electricity when charge is driven round a circuit is called:
a) Electromotive source
b) Electromotive force (emf)
c) Potential energy
d) Kinetic energy
B
77.
The electromotive force of a battery or cell is the voltage between its terminals when:
a) The circuit is closed
b) The circuit is open
c) Its internal resistance is minimum
d) Its internal resistance is maximum
B
78.
The electromotive force (emf) is defined by the relation:
a) E = IR
b) E = IQ
W
V
c) E =
d) E =
q
q
C
79.
When we connect two given cells in parallel the total emf of the combination is equal to:
a) Zero
b) Sum of emfs of the individual cells
c) The emf of the small cell
d) The emf of the large cell
D
80.
By electromotive force:
a) Sound is produced
c) Light is produced
D
b) Heat is produced
d) Current is produced
Electric generators convert:
a) Mechanical energy into electrical energy
c) Heat energy into electrical energy
b) Electrical energy into mechanical energy
d) Kinetic energy into electrical energy
Thermocouples convert:
a) Electrical energy into heat energy
c) Kinetic energy into potential energy
b) Heat energy into electrical energy
d) Light energy into electrical energy
Photovoltaic cell converts:
a) Light energy into electrical energy
c) Chemical energy into electrical energy
b) Heat energy into electrical energy
d) None of these
The unit of electromotive force is:
a) Coulomb per second (ampere)
c) Joule per coulomb (volt)
b) Joule per second (watt)
d) Coulomb per volt (farad)
81.
82.
83.
84.
A
B
A
C
85.
The source of emf converts some form of energy into:
a) Electrostatic potential (electrical) energy
b) Kinetic energy
c) Chemical energy
d) Nuclear energy
A
86.
Electromotive force is closely related to:
a) Electric field intensity
c) Potential difference
C
b) Magnetic flux density
d) None of these
Batteries or cells convert:
a) Heat energy into electrical energy
c) Nuclear energy into electrical energy
b) Chemical energy into electrical energy
d) Kinetic energy into electrical energy
87.
88.
B
The emf of a source is equal to the potential difference across the terminals of the source when its
internal resistance is:
a) Zero
b) Infinite
c) Zero or infinite
d) None of these
YASIR MUKHTAR
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A
PHYSICS
CHAPTER # 13
Current Electricity
89.
Terminal potential difference ‘Vt’ of a battery of internal resistance ‘r’ and emf ‘E’ is:
a) Vt = E - Ir
b) Vt = E + Ir
E
c) Vt = EIr
d) Vt =
IR
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A