120 Important MCQs (Set-1 of Basic to Moderate MCQs) on Current & Electricity, Physics (Unit-Wise MCQs Practice):

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This post contains carefully selected Multiple-Choice Questions (MCQs) (Set-2 from Basic to Expert Level) from Current & Electricity of Physics, prepared strictly according to the latest board exam syllabus. These MCQs include a balanced combination of conceptual understanding and numerical problem-solving, making them revision-friendly, exam-oriented, and high-scoring.

Whether you are preparing for annual board examinations, chapter tests, or competitive entry tests, this comprehensive MCQ collection thoroughly covers the fundamental principles of Current & Electricity—starting from Steady Current and Ohm’s Law to Kirchhoff’s Laws and Potentiometers—helping students build strong conceptual clarity and numerical confidence.

This unit-wise MCQ set includes questions from:
• Steady Current and Drift Velocity in Conductors
• Ohm’s Law and its applications
• Electrical Resistance and Factors affecting Resistance
• Specific Resistance or Resistivity, Conductance, and Conductivity
• Effect of Temperature on Resistance and Temperature Coefficient of Resistance
• EMF of Cells, Internal Resistance, and Terminal Voltage
• Electric Power, Maximum Power Transfer, and Energy Dissipation
• Thermocouples, Thermistors, and Resistance Thermometers
• Kirchhoff’s Current Law (KCL) and Voltage Law (KVL)
• Wheatstone Bridge and Potentiometer – theory and numerical applications

Each MCQ is provided with the correct answer and a clear, concise explanation, helping students to:

Strengthen conceptual understanding of current, voltage, and resistance phenomena
Avoid common mistakes in numerical problems involving Ohm’s law, EMF, and resistivity
Improve problem-solving skills for series-parallel circuits, bridges, and potentiometer setups
Master practical applications of Kirchhoff’s Laws and maximum power transfer
Achieve maximum marks in the MCQ section

This all-in-one Current & Electricity MCQ collection is an essential revision tool for all students aiming to excel in Physics exams and fully master the concepts of current, resistance, EMF, power, thermoelectric effects, and circuit analysis.

MCQ No. 1

Value of current for an open circuit is:

a. Zero
b. Infinity
c. Maximum
d. Small

Correct answer: a. Zero

Explanation:
In an open circuit resistance is infinite, so by Ohm’s law $I = V/R = 0$ .

MCQ No. 2

The resistance of a 20 cm wire is 10 Ω. When stretched to 40 cm, its new resistance becomes:

a. 10 Ω
b. 40 Ω
c. 30 Ω
d. 20 Ω

Correct answer: b. 40 Ω

Explanation:
When length doubles and area halves, resistance becomes four times:
$R' = 4R = 40\,\Omega$ .

MCQ No. 3

What is the resistance of a carbon resistor having brown, black and brown bands?

a. 100 Ω
b. 1000 Ω
c. 10 Ω
d. 1 Ω

Correct answer: a. 100 Ω

Explanation:
Brown = 1, Black = 0, multiplier Brown = ×10 → $10×10 = 100\,\Omega$ .

MCQ No. 4

In series combination, if potential differences are in ratio 2 : 3, then resistances are in ratio:

a. 2 : 3
b. 3 : 2
c. 4 : 9
d. 9 : 4

Correct answer: a. 2 : 3

Explanation:
In series circuits, voltage is directly proportional to resistance.

MCQ No. 5

A wire is stretched so that its radius becomes half. The new resistance becomes:

a. 2 times
b. 4 times
c. 8 times
d. 16 times

Correct answer: d. 16 times

Explanation:
Length becomes four times and area becomes one-fourth, so resistance becomes 16 times.

MCQ No. 6

Tolerance ±10% corresponds to which colour?

a. White
b. Silver
c. Gold
d. Violet

Correct answer: b. Silver

Explanation:
Silver band represents ±10% tolerance.

MCQ No. 7

Three bulbs of 50 W, 100 W and 200 W are connected in series. Which glows brightest?

a. 50 W
b. 100 W
c. 200 W
d. All equal

Correct answer: a. 50 W

Explanation:
Lower wattage bulb has higher resistance; in series it dissipates maximum power.

MCQ No. 8

When a wire of resistance R is cut into two equal parts, resistance of each part becomes:

a. Double
b. Half
c. Same
d. One fourth

Correct answer: b. Half

Explanation:
Resistance is proportional to length; halving length halves resistance.

MCQ No. 9

The drift velocity of electrons is of the order of:

a. $10^{-2}\,m/s$
b. $10^{-3}\,m/s$
c. $10^{3}\,m/s$
d. $10^{6}\,m/s$

Correct answer: b. $10^{-3}\,m/s$

Explanation:
Drift velocity of electrons in conductors is very small, about $10^{-3}\,m/s$

MCQ No. 10

When a battery is on charging, emf (ε) and terminal potential difference (Vₜ) are related as:

a. ε > Vₜ
b. ε < Vₜ
c. ε = Vₜ
d. Any of these

Correct answer: a. ε > Vₜ

Explanation:
During charging, applied emf must be greater than terminal voltage.

MCQ No. 11

For an open circuit, terminal potential difference $V_t$ is:

a. $V_t = 2\,emf$
b. $V_t = emf$
c. $V_t > emf$
d. $V_{t} < e m f$

Correct answer: b. $V_t = emf$

Explanation:
When the circuit is open, no current flows, so there is no internal voltage drop and terminal voltage equals emf.

MCQ No. 12

Kirchhoff’s first rule is in accordance with law of conservation of:

a. Energy
b. Momentum
c. Mass
d. None of these

Correct answer: d. None of these

Explanation:
Kirchhoff’s first law is based on conservation of charge.

MCQ No. 13

In an electrolyte, the charge carriers are:

a. Positive ions and electrons
b. Electrons
c. Positive and negative ions
d. Protons

Correct answer: c. Positive and negative ions

Explanation:
Current in electrolytes is carried by both positive and negative ions.

MCQ No. 14

Slope of graph between V on X-axis and I on Y-axis is:

a. Resistance
b. Conductance
c. Resistivity
d. Conductivity

Correct answer: b. Conductance

Explanation:
Slope = I/V, which equals conductance.

MCQ No. 15

Heat generated by a 50 W bulb in one hour is:

a. 36000 J
b. 48000 J
c. 18000 J
d. 180000 J

Correct answer: d. 180000 J

Explanation:
Energy = Power × Time = 50 × 3600 = 180000 J.

MCQ No. 16

Siemen is the unit of:

a. Resistivity
b. Resistance
c. Conductivity
d. Conductance

Correct answer: d. Conductance

Explanation:
Siemen (S) is the SI unit of conductance.

MCQ No. 17

If a resistor is traversed in direction of current, change in potential is:

a. Zero
b. Negative
c. Positive
d. Absolute

Correct answer: b. Negative

Explanation:
Potential decreases along the direction of current through a resistor.

MCQ No. 18

$1.0\times10^{7}$ electrons flow in $1\,\mu s$ . Value of current is:

a. $1.6\times10^{-6}A$
b. $1.6\times10^{-19}A$
c. 1.6 A
d. 9.6 A

Correct answer: a. $1.6\times10^{-6}A$

Explanation:
$I = ne/t = (10^7×1.6×10^{-19})/(10^{-6}) = 1.6×10^{-6}A$ .

MCQ No. 19

An ideal current source has resistance:

a. Zero
b. Finite
c. Infinite
d. Depends on use

Correct answer: c. Infinite

Explanation:
An ideal current source must maintain constant current, so its internal resistance is infinite.

MCQ No. 20

The unit of conductivity is:

a. mho m⁻¹
b. ohm m⁻¹
c. siemen
d. mho

Correct answer: a. mho m⁻¹

Explanation:
Conductivity is reciprocal of resistivity; its SI unit is mho per meter.

MCQ No. 21

The current flowing through each resistor of equal resistance in parallel combination is:

a. Same
b. Different
c. Zero
d. Infinite

Correct answer: a. Same

Explanation:
In parallel, all resistors have the same voltage. Since resistances are equal, currents are also equal.

MCQ No. 22

Magnetic effect of current is used in:

a. Toaster
b. Electric motor
c. Electric iron
d. D.C battery

Correct answer: b. Electric motor

Explanation:
Electric motors work on the magnetic effect of current.

MCQ No. 23

$6.25\times10^{18}$ electrons possess charge equal to:

a. 1 C
b. 2 C
c. 3 C
d. 4 C

Correct answer: a. 1 C

Explanation:
Charge of one electron is $1.6×10^{-19}C$ .
So $6.25×10^{18}×1.6×10^{-19}=1C$ .

MCQ No. 24

Equivalent resistance of two wires in parallel is $6/5\,\Omega$ . If one wire has resistance 2 Ω, the other resistance is:

a. 3 Ω
b. 0.5 Ω
c. 5 Ω
d. 1.5 Ω

Correct answer: a. 3 Ω

Explanation:
Using $1/R = 1/R_1 + 1/R_2$ , the unknown resistance comes out to be 3 Ω.

MCQ No. 25

If 5 A current flows for 2 minutes, the charge passed is:

a. 500 C
b. 600 C
c. 400 C
d. 10 C

Correct answer: b. 600 C

Explanation:
$q = It = 5×120 = 600C$

MCQ No. 26

For a closed circuit, emf ε and terminal voltage Vₜ are related as:

a. ε > Vₜ
b. ε < Vₜ
c. ε = Vₜ
d. All of these

Correct answer: a. ε > Vₜ

Explanation:
Some voltage is lost across internal resistance, so emf is greater than terminal voltage.

MCQ No. 27

Value of current for an ideal short circuit is:

a. Zero
b. Infinity
c. Moderate
d. Minimum

Correct answer: b. Infinity

Explanation:
Short circuit means resistance is zero, so current becomes extremely large.

MCQ No. 28

Internal resistance of a cell is mainly due to:

a. Static charges
b. Electrodes
c. Electrolyte
d. Electrolysis

Correct answer: c. Electrolyte

Explanation:
Electrolyte opposes flow of charge, producing internal resistance.

MCQ No. 29

If cost per kWh is Rs. 2, then cost of operating two 100 W fans for 10 hours is:

a. Rs. 4
b. Rs. 2
c. Rs. 6
d. Rs. 1

Correct answer: a. Rs. 4

Explanation:
Total power = 200 W = 0.2 kW
Energy = 0.2 × 10 = 2 kWh
Cost = 2 × 2 = Rs. 4.

MCQ No. 30

Wheatstone bridge is based on Kirchhoff’s:

a. 1st rule
b. 2nd rule
c. 3rd rule
d. 4th rule

Correct answer: b. 2nd rule

Explanation:
Wheatstone bridge uses Kirchhoff’s voltage law (second rule).

MCQ No. 31

Three bulbs of 40 W, 100 W and 200 W are connected in parallel. Which bulb gives maximum brightness?

a. 40 W
b. 100 W
c. 200 W
d. All same

Correct answer: c. 200 W

Explanation:
In parallel, voltage is same. Higher wattage bulb draws more current and glows brightest.

MCQ No. 32

Kirchhoff’s second rule is based on:

a. Energy conservation
b. Mass conservation
c. Charge conservation
d. Momentum conservation

Correct answer: a. Energy conservation

Explanation:
Kirchhoff’s voltage law follows the law of conservation of energy.

MCQ No. 33

An ideal voltmeter should have resistance:

a. Zero
b. Infinite
c. MΩ
d. kΩ

Correct answer: b. Infinite

Explanation:
An ideal voltmeter must not draw current, so its resistance is infinite.

MCQ No. 34

A voltmeter connected across a battery in a working circuit measures:

a. emf
b. Terminal potential difference
c. Internal resistance
d. Current

Correct answer: b. Terminal potential difference

Explanation:
When current flows, voltmeter reads terminal voltage, not emf.

MCQ No. 35

Potentiometer is used to:

a. Measure potential difference
b. Compare e.m.f of cells
c. Find internal resistance
d. All of these

Correct answer: d. All of these

Explanation:
Potentiometer can measure voltage, compare emfs and determine internal resistance.

MCQ No. 36

Tolerance for silver colour band is:

a. ±10%
b. ±15%
c. ±20%
d. ±5%

Correct answer: a. ±10%

Explanation:
Silver band indicates ±10% tolerance.

MCQ No. 37

A resistor is cut into two equal parts. Its resistivity becomes:

a. Half
b. Same
c. Double
d. Four times

Correct answer: b. Same

Explanation:
Resistivity depends on material and temperature, not dimensions.

MCQ No. 38

The SI unit of resistivity is:

a. Ωm²
b. Ωm⁻¹
c. Ω
d. Ωm

Correct answer: d. Ωm

Explanation:
From $\rho = RA/L$ , unit of resistivity is ohm-meter.

MCQ No. 39

Which factor does NOT affect conductivity of a PN junction diode?

a. Doping
b. Temperature
c. Voltage
d. Pressure

Correct answer: d. Pressure

Explanation:
Conductivity depends on doping, temperature and voltage, not pressure.

MCQ No. 40

A potentiometer circuit gives continuously varying:

a. Potential difference
b. Current
c. Resistance
d. Both A and C

Correct answer: d. Both A and C

Explanation:
Sliding contact changes effective resistance and hence potential difference.

MCQ No. 41

Which material has negative temperature coefficient of resistivity?

a. Steel
b. Iron
c. Tungsten
d. Silicon

Correct answer: d. Silicon

Explanation:
In semiconductors like silicon, resistance decreases as temperature increases.

MCQ No. 42

Unit mho m⁻¹ represents:

a. Conductance
b. Conductivity
c. Resistance
d. Resistivity

Correct answer: b. Conductivity

Explanation:
Conductivity is reciprocal of resistivity, so its unit is mho per meter.

MCQ No. 43

During danger, an electric eel can produce potential difference up to:

a. 160 V
b. 220 V
c. 440 V
d. 600 V

Correct answer: d. 600 V

Explanation:
Electric eel can generate shocks up to about 600 V for protection.

MCQ No. 44

The reciprocal of resistance is called:

a. Reactance
b. Inductance
c. Conductance
d. Conductivity

Correct answer: c. Conductance

Explanation:
Conductance = 1 / Resistance.

MCQ No. 45

A 100 W bulb is switched on for half an hour. Heat produced is:

a. 0.36 MJ
b. 18 MJ
c. 3 kJ
d. 0.18 MJ

Correct answer: d. 0.18 MJ

Explanation:
Energy = P × t = 100 × 1800 = 180000 J = 0.18 MJ.

MCQ No. 46

Resistance tolerance for gold colour is:

a. ±50%
b. ±30%
c. ±20%
d. ±5%

Correct answer: d. ±5%

Explanation:
Gold band represents ±5% tolerance.

MCQ No. 47

mho m⁻¹ is SI unit of:

a. Conductance
b. Conductivity
c. Resistance
d. Resistivity

Correct answer: b. Conductivity

Explanation:
Conductivity is measured in mho per meter.

MCQ No. 48

Which of the following is a source of electric current?

a. Transformer
b. Electric generator
c. AC motor
d. DC motor

Correct answer: b. Electric generator

Explanation:
Generators convert mechanical energy into electrical energy.

MCQ No. 49

Red colour in carbon resistor has numerical value:

a. 1
b. 2
c. 3
d. 4

Correct answer: b. 2

Explanation:
Red band corresponds to digit 2 in colour coding.

MCQ No. 50

Current through a 100 Ω resistor connected to 220 V is:

a. 22000 A
b. 22 A
c. 2.2 A
d. 0.45 A

Correct answer: c. 2.2 A

Explanation:
Using Ohm’s law: I = V/R = 220/100 = 2.2 A.

MCQ No. 51

Maximum power is delivered to a load resistance R when internal resistance of source is:

a. Zero
b. Infinite
c. Equal to R
d. Equal to R/2

Correct answer: c. Equal to R

Explanation:
According to maximum power transfer theorem, maximum power is obtained when load resistance equals internal resistance.

MCQ No. 52

Current flowing from higher potential to lower potential is called:

a. Electric current
b. Conventional current
c. Either of these
d. None

Correct answer: b. Conventional current

Explanation:
Conventional current flows from positive (higher potential) to negative (lower potential).

MCQ No. 53

When a wire is cut into two equal parts, resistivity of each part:

a. Becomes half
b. Remains unchanged
c. Becomes double
d. Becomes four times

Correct answer: b. Remains unchanged

Explanation:
Resistivity depends only on material and temperature.

MCQ No. 54

Thermo-couple converts heat energy into:

a. Atomic energy
b. Solar energy
c. Electrical energy
d. Nuclear energy

Correct answer: c. Electrical energy

Explanation:
Thermocouple produces electrical voltage from temperature difference.

MCQ No. 55

Numerical value of black colour in carbon resistors is:

a. 0
b. 1
c. 2
d. 3

Correct answer: a. 0

Explanation:
Black band represents zero.

MCQ No. 56

Heat produced in a resistor is calculated using:

a. Faraday’s law
b. Lenz’s law
c. Joule’s law
d. Kirchhoff’s rule

Correct answer: c. Joule’s law

Explanation:
Joule’s law: H = I²Rt.

MCQ No. 57

SI unit of resistivity is:

a. Ωm
b. Ωm⁻¹
c. Ωm⁻²
d. Ω⁻¹m⁻¹

Correct answer: a. Ωm

Explanation:
From $\rho = RA/L$ , unit is ohm-meter.

MCQ No. 58

Which instrument measures potential without drawing current?

a. Potentiometer
b. Ammeter
c. Voltmeter
d. Galvanometer

Correct answer: a. Potentiometer

Explanation:
Potentiometer measures voltage without drawing current.

MCQ No. 59

Kirchhoff’s voltage rule represents conservation of:

a. Energy
b. Momentum
c. Charge
d. Angular momentum

Correct answer: a. Energy

Explanation:
Kirchhoff’s second law is based on conservation of energy.

MCQ No. 60

Three 1 Ω resistors form a triangle. Resistance between any two corners is:

a. 2/3 Ω
b. 3/2 Ω
c. 1/2 Ω
d. 3 Ω

Correct answer: a. 2/3 Ω

Explanation:
Equivalent resistance of triangular arrangement comes out to 2/3 Ω.

MCQ No. 61

Drift velocity of electrons increases when:

a. Temperature increases
b. Potential difference increases
c. Length of wire increases
d. Area decreases

Correct answer: b. Potential difference increases

Explanation:
Drift velocity is directly proportional to applied electric field, which increases with potential difference.

MCQ No. 62

If length of a conductor is doubled, its resistance becomes:

a. Half
b. Same
c. Double
d. Four times

Correct answer: c. Double

Explanation:
Resistance is directly proportional to length (R ∝ L).

MCQ No. 63

Electrical energy supplied by a source is given by:

a. V/I
b. VI
c. VIt
d. I²R

Correct answer: c. VIt

Explanation:
Energy = Power × time = VI × t.

MCQ No. 64

Which factor does NOT affect resistance of a wire?

a. Length
b. Area
c. Material
d. Current

Correct answer: d. Current

Explanation:
Resistance depends on length, area, and material, not on current.

MCQ No. 65

Combination of resistors used to divide voltage is called:

a. Series circuit
b. Parallel circuit
c. Voltage divider
d. Current divider

Correct answer: c. Voltage divider

Explanation:
Series resistors divide applied voltage across them.

MCQ No. 66

Terminal potential difference of a cell is zero when:

a. Circuit is open
b. Current is small
c. Cell is charging
d. Cell is short-circuited

Correct answer: d. Cell is short-circuited

Explanation:
During short circuit, external resistance is zero, so terminal voltage becomes zero.

MCQ No. 67

The slope of V–I graph gives:

a. Current
b. Voltage
c. Resistance
d. Power

Correct answer: c. Resistance

Explanation:
From Ohm’s law, slope (V/I) equals resistance.

MCQ No. 68

Kirchhoff’s current law is based on conservation of:

a. Energy
b. Momentum
c. Charge
d. Mass

Correct answer: c. Charge

Explanation:
Total charge entering a junction equals charge leaving it.

MCQ No. 69

Internal resistance of an ideal cell is:

a. Zero
b. Very large
c. One ohm
d. Infinite

Correct answer: a. Zero

Explanation:
Ideal cells are assumed to have no internal resistance.

MCQ No. 70

A fuse wire is made of material having:

a. High melting point
b. Low resistance
c. Low melting point
d. High conductivity

Correct answer: c. Low melting point

Explanation:
Fuse melts quickly during excess current to protect the circuit.

MCQ No. 71

In a parallel circuit, voltage across each resistor is:

a. Same
b. Different
c. Zero
d. Depends on resistance

Correct answer: a. Same

Explanation:
In parallel, each branch is directly connected to the supply, so all have the same voltage.

MCQ No. 72

If a resistor of 100 Ω is connected across 220 V, the current flowing is:

a. 2.2 A
b. 0.45 A
c. 22 A
d. 1 A

Correct answer: a. 2.2 A

Explanation:
From Ohm’s law: $I = V/R = 220 / 100 = 2.2\ \mathrm{A}$ .

MCQ No. 73

Resistance of a wire depends on:

a. Material, length, area
b. Current
c. Voltage
d. Time

Correct answer: a. Material, length, area

Explanation:
R = ρL/A; depends on resistivity, length, and cross-sectional area.

MCQ No. 74

Tolerance of gold band in a resistor is:

a. ±5%
b. ±10%
c. ±15%
d. ±20%

Correct answer: a. ±5%

Explanation:
Gold band indicates ±5% variation in resistance value.

MCQ No. 75

The unit of conductivity is:

a. Ohm
b. Siemens
c. Ohm-meter
d. Mho-meter⁻¹

Correct answer: d. Mho m⁻¹

Explanation:
Conductivity is reciprocal of resistivity; SI unit is mho per meter.

MCQ No. 76

The potential difference between the head and tail of an electric eel can be up to:

a. 500 V
b. 600 V
c. 700 V
d. 800 V

Correct answer: b. 600 V

Explanation:
Side information: Electric eels can generate a maximum potential difference of about 600 V.

MCQ No. 77

Resistance tolerance for gold color is:

a. ±50%
b. ±30%
c. ±20%
d. ±5%

Correct answer: d. ±5%

Explanation:
The variation in marked value of resistance is called tolerance. Gold band indicates ±5%.

MCQ No. 78

SI unit of temperature coefficient of resistivity is:

a. Ohm
b. Ohm-meter
c. T
d. T⁻¹

Correct answer: d. T⁻¹

Explanation:
Temperature coefficient α = (Δρ)/(ρ₀ ΔT); SI unit is K⁻¹ (T⁻¹).

MCQ No. 79

A substance having negative temperature coefficient of resistivity is:

a. Iron
b. Tungsten
c. Carbon
d. Gold

Correct answer: c. Carbon

Explanation:
For carbon, resistivity decreases with increasing temperature, giving a negative temperature coefficient.

MCQ No. 80

Heat generated by a 40 W bulb in one hour is:

a. 140 J
b. 1,440 J
c. 14,400 J
d. 144,000 J

Correct answer: d. 144,000 J

Explanation:
Energy = Power × Time = 40 W × 3600 s = 144,000 J.

MCQ No. 81

If a wire has twice the diameter of another identical wire, its resistance is:

a. Same as R
b. 4 R
c. 2 R
d. Half of R

Correct answer: a. Same as R

Explanation:
Resistivity depends on material; doubling diameter changes area, but resistance formula R = ρL/A adjusts, so resistance stays same if material and length are identical.

MCQ No. 82

Color codes on a resistor are used to calculate:

a. Nature of resistor
b. Numerical value of resistance
c. Potential difference
d. Current

Correct answer: b. Numerical value of resistance

Explanation:
Color bands represent numerical values according to standard tables.

MCQ No. 83

Thermistor converts change in temperature into:

a. Light energy
b. Electric voltage
c. Heat
d. Sound

Correct answer: b. Electric voltage

Explanation:
Thermistor is heat-sensitive; resistance changes with temperature, producing a corresponding voltage change in a circuit.

MCQ No. 84

A battery moves a charge of 40 C in 20 s. The current is:

a. 2 A
b. 0.5 A
c. 80 A
d. 800 A

Correct answer: a. 2 A

Explanation:
I = q / t = 40 C / 20 s = 2 A.

MCQ No. 85

If a 500 Ω resistor has a fourth band of silver color, its upper maximum resistance is:

a. 600 Ω
b. 550 Ω
c. 450 Ω
d. 400 Ω

Correct answer: b. 550 Ω

Explanation:
Silver indicates ±10% tolerance. Variation = 10% of 500 Ω = 50 Ω. Maximum resistance = 500 + 50 = 550 Ω.

MCQ No. 86

A rheostat can operate as:

a. Amplifier
b. Potential divider
c. Oscillator
d. Transformer

Correct answer: b. Potential divider

Explanation:
A rheostat can be used to vary resistance in a circuit, acting as a potential divider.

MCQ No. 87

For an ohmic device, the graph between V and I is:

a. A straight line
b. Curve
c. Hyperbola
d. Parabola

Correct answer: a. A straight line

Explanation:
Ohm’s law: I ∝ V; the graph of current versus voltage is linear.

MCQ No. 88

By increasing the temperature of a conductor, the flow rate of charges:

a. Increases
b. Remains constant
c. Changes exponentially
d. Decreases

Correct answer: d. Decreases

Explanation:
I = V/R; resistance increases with temperature for metals, so current decreases.

MCQ No. 89

Heat-sensitive resistors are called:

a. Resistors
b. Capacitors
c. Thermistors
d. Inductors

Correct answer: c. Thermistors

Explanation:
Thermistors change resistance with temperature, converting temperature variations into electrical signals.

MCQ No. 90

Magnitude of drift velocity of electrons is of the order of:

a. 10 m/s
b. 1 m/s
c. 10⁻³ m/s
d. 10⁶ m/s

Correct answer: c. 10⁻³ m/s

Explanation:
Drift velocity V_d ≈ 10⁻³ m/s (about 1 mm/s) for typical conductors.

MCQ No. 91

If the fourth band is missing on a resistor, its tolerance is:

a. ±5%
b. ±10%
c. ±15%
d. ±20%

Correct answer: d. ±20%

Explanation:
No tolerance band indicates a default tolerance of ±20%.

MCQ No. 92

The proportionality constant between current and potential difference is:

a. 1/ρ
b. ρ
c. 1/R
d. R

Correct answer: c. 1/R

Explanation:
Ohm’s law: I = V/R, so proportionality constant between I and V is 1/R.

MCQ No. 93

SI unit of temperature coefficient of resistivity is:

a. Ohm
b. Ohm-m
c. T
d. T⁻¹

Correct answer: d. T⁻¹

Explanation:
Temperature coefficient α = (Δρ)/(ρ₀ ΔT); SI unit is K⁻¹ (T⁻¹).

MCQ No. 94

A substance having negative temperature coefficient of resistivity is:

a. Iron
b. Tungsten
c. Carbon
d. Gold

Correct answer: c. Carbon

Explanation:
Resistivity of carbon decreases with increasing temperature, giving negative temperature coefficient.

MCQ No. 95

In carbon resistors, the value of blue color is:

a. 7
b. 6
c. 8
d. 9

Correct answer: b. 6

Explanation:
Blue corresponds to 6 in standard color code of carbon resistors.

MCQ No. 96

Heat generated by a 40 W bulb in one hour is:

a. 140 J
b. 1440 J
c. 14400 J
d. 144000 J

Correct answer: d. 144000 J

Explanation:
H = P × t = 40 W × 3600 s = 144000 J.

MCQ No. 97

A certain wire has resistance R. The resistivity of another wire of identical material but with twice its diameter is:

a. R
b. 4 R
c. 2 R
d. Same as R

Correct answer: d. Same as R

Explanation:
Resistivity depends only on material, not on dimensions. R = ρ L / A.

MCQ No. 98

Color codes are used to calculate:

a. Nature of resistor
b. Numerical value of resistance
c. Potential difference
d. Current

Correct answer: b. Numerical value of resistance

Explanation:
Color codes represent the numerical value of carbon resistances.

MCQ No. 99

The thermistor converts change of temperature into:

a. Light energy
b. Electric voltage
c. Heat
d. Sound

Correct answer: b. Electric voltage

Explanation:
A thermistor is heat-sensitive; it converts temperature variation into electrical signals.

MCQ No. 100

A battery moves a charge of 40 C around a circuit at constant rate in 20 s. The current will be:

a. 2 A
b. 0.5 A
c. 80 A
d. 800 A

Correct answer: a. 2 A

Explanation:
I = q / t = 40 C / 20 s = 2 A.

MCQ No. 101

If the resistance of 500 Ω has fourth band of silver colour, then its upper maximum resistance will be:

a. 600 Ω
b. 550 Ω
c. 450 Ω
d. 400 Ω

Correct answer: b. 550 Ω

Explanation:
Silver has ±10% tolerance. Maximum resistance = 500 + 10% of 500 = 550 Ω.

MCQ No. 102

A 100 W bulb is switched on for half an hour. Heat lost due to flow of current is:

a. 0.36 MJ
b. 18 MJ
c. 3 kJ
d. 0.18 MJ

Correct answer: d. 0.18 MJ

Explanation:
Energy, W = P × t = 100 W × 1800 s = 180000 J = 0.18 MJ.

MCQ No. 103

The equivalent resistance of three resistors arranged in a combination (1 in series with 2 in parallel, each 4 Ω) is:

a. 4 Ω
b. 12 Ω
c. 8/3 Ω
d. 3/8 Ω

Correct answer: c. 8/3 Ω

Explanation:
Req = (Product of resistances) / (Sum of resistances) for parallel part, then add series resistance = 8/3 Ω.

MCQ No. 104

Resistance tolerance for gold color is:

a. ±50%
b. ±30%
c. ±20%
d. ±5%

Correct answer: d. ±5%

Explanation:
Gold band indicates ±5% variation in resistor value.

MCQ No. 105

SI unit of conductivity is:

a. Conductance
b. Conductivity
c. Resistance
d. Resistivity

Correct answer: b. Conductivity

Explanation:
Conductivity σ = 1/ρ; SI unit is mho m⁻¹.

MCQ No. 106

A rheostat can operate as:

a. Amplifier
b. Potential divider
c. Oscillator
d. Transformer

Correct answer: b. Potential divider

Explanation:
A rheostat is a variable resistor that can be used as a potential divider to vary voltage in a circuit.

MCQ No. 107

Kirchhoff’s second rule is based on:

a. Energy conservation
b. Mass conservation
c. Charge conservation
d. Momentum conservation

Correct answer: a. Energy conservation

Explanation:
Kirchhoff’s second rule (voltage law) states that the sum of potential differences around a closed loop is zero, in accordance with the law of conservation of energy.

MCQ No. 108

For an ohmic device, the graph between V and I is:

a. A straight line
b. Curve
c. Hyperbola
d. Parabola

Correct answer: a. A straight line

Explanation:
For an ohmic device, V ∝ I, so the V-I graph is a straight line through the origin.

MCQ No. 109

By increasing the temperature of a conductor, the flow rate of charges:

a. Increases
b. Remains constant
c. Changes exponentially
d. Decreases

Correct answer: d. Decreases

Explanation:
Resistance of a conductor increases with temperature. I = V / R, so current decreases as R increases.

MCQ No. 110

Heat sensitive resistors are called:

a. Resistors
b. Capacitors
c. Thermistors
d. Inductors

Correct answer: c. Thermistors

Explanation:
Thermistors are resistors whose resistance changes significantly with temperature, converting thermal changes into electrical signals.

MCQ No. 111

Magnitude of drift velocity is of the order of:

a. 10 m/s
b. 1 m/s
c. 10⁻³ m/s
d. 10⁶ m/s

Correct answer: c. 10⁻³ m/s

Explanation:
Drift velocity of electrons in a conductor is typically very small, around 10⁻³ m/s.

MCQ No. 112

If the fourth band is missing on a resistor, its tolerance is:

a. ±5%
b. ±10%
c. ±15%
d. ±20%

Correct answer: d. ±20%

Explanation:
Absence of a tolerance band indicates a default tolerance of ±20% for the resistor.

MCQ No. 113

The proportionality constant between current and potential difference is:

a. 1 / ρ
b. ρ
c. 1 / R
d. R

Correct answer: c. 1 / R

Explanation:
By Ohm’s law, I = V / R, so 1 / R is the proportionality constant between current and voltage.

MCQ No. 114

The S.I. unit of temperature coefficient of resistivity is:

a. ohm
b. ohm-m
c. T
d. T⁻¹

Correct answer: d. T⁻¹

Explanation:
Temperature coefficient α = (Δρ / ρ₀) × (1 / ΔT), so its SI unit is reciprocal temperature, T⁻¹.

MCQ No. 115

A substance having negative temperature coefficient of resistivity is:

a. Iron
b. Tungsten
c. Carbon
d. Gold

Correct answer: c. Carbon

Explanation:
Carbon’s resistivity decreases with temperature; it has a negative temperature coefficient.

MCQ No. 116

In carbon resistors, the value of blue colour is:

a. 7
b. 6
c. 8
d. 9

Correct answer: b. 6

Explanation:
According to the colour code table for carbon resistors, blue represents 6.

MCQ No. 117

Heat generated by a 40 W bulb in one hour is:

a. 140 J
b. 1440 J
c. 14400 J
d. 144000 J

Correct answer: d. 144000 J

Explanation:
H = P × t = 40 × 3600 = 144000 J.

MCQ No. 118

A certain wire has resistance R. The resistivity of another wire of identical material with twice its diameter is:

a. R
b. 4 R
c. 2 R
d. Same as R

Correct answer: d. Same as R

Explanation:
Resistivity is independent of dimensions. R = ρ L / A.

MCQ No. 119

Color codes are used to calculate:

a. Nature of resistor
b. Numerical value of resistance
c. Potential difference
d. Current

Correct answer: b. Numerical value of resistance

Explanation:
Colour codes provide the numerical value of carbon resistances.

MCQ No. 120

A battery moves a charge of 40 C around a circuit at constant rate in 20 s. The current will be:

a. 2 A
b. 0.5 A
c. 80 A
d. 800 A

Correct answer: a. 2 A

Explanation:
I = q / t = 40 / 20 = 2 A.

120 High-Scoring MCQs on Current & Electricity (Set-2 Basic to Expert Level MCQs)

120 Important MCQs (Set-1 of Basic to Moderate MCQs) on Current & Electricity, Physics (Unit-Wise MCQs Practice):

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