Current Electricity MCQs with Explanation

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Current Electricity can be classified as a branch of Physics that deals with the motion of electric charge. Electric Current can be defined as the rate of flow of electric charge through any cross-section of a conductor.

Electric Current is represented using the symbol I and is calculated as

\(I= \frac{Q} {t}\)

Where

Q refers to the total charge flowing and
t refers to the total time.

The SI unit of current is Amperes (A) and it is a scalar quantity.

The direction of the electric current is taken as the direction of the motion of positively charged particles and opposite to the direction of the negatively charged particles. Current Density at any point is defined as the ratio of the current at that point in the conductor to the area of the cross-section of the conductor. It is a vector quantity and its SI unit is A/m².

Discover about the Chapter video:

Current Electricity Detailed Video Explanation:

Here are some important MCQs on Current Electricity for the students to test and assess their knowledge on the given topic.

Ques. _______is known as the rate of flow of electric charges through any cross-section of a conductor.

Electric Field
Electric Flux
Electric Charge
Electric Current

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Ans. (D) Electric Current

Explanation: Electric current is a stream of charged particles moving through an electrical conductor. The charge can be negatively charged electrons or positively charged like protons, positive ions, and holes. The magnitude of electric current is to be measured in coulombs per second. The common unit is known as Ampere or amp.

Ques. Combine four resistors 5.5 Ω, 2 Ω, 3 Ω, and 4.5 Ω so that their total is maximum:

14 Ω
15 Ω
15.5 Ω
13.5 Ω

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Ans. (B) 15

Explanation: All the resistors that are 5.5 Ω,2 Ω,3 Ω, and 4.5 Ω will be added together to form the maximum total which will amount to 15.

Ques. If 500 Ω resistance is made up of five 100 Ω resistances of tolerance of 5 percent, then the tolerance of this combination is

5 percent
9 percent
10 percent
25 percent

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Ans. (A) 5 percent

Explanation: Tolerance is the indicator of how much the measured value of its actual resistance is different from its theoretical value and is calculated using percentages. 10 percent tolerance is indicated by the silver band, 5 percent tolerance by the gold band, and 1 percent or less by green or brown bands.

Each 100-ohm resistance has a tolerance of 5%. i.e. 5 ohms.
The total tolerance of 5 such resistances is 5 × 5 = 25 ohms.
The total resistance of the combination is 5 × 100 = 500 ohms.
Tolerance of the combination will be -
Tolerance = 25 / 500 × 100 %
Tolerance = 5 %
Therefore, the tolerance of the combination will be 5 %

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Ques. How many different ways three 1 Ω can they be combined?

Five ways
Eight ways
Four ways
Three ways

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Ans. (C) Four ways

Explanation: There are four ways three 1 Ω can be combined.

The first way- All in parallel.
The second way- Two in series, others in parallel.
The third way- Two in parallel and others in series.
The fourth way- All in series.

Read More: Types of Resistors

Ques. From which part of the atom does electric current originate?

Positively charged protons
Negatively charged electrons
Positive ions
Nucleus

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Ans. (B) Negatively charged electrons

Explanation: Electric current originates from electrons. Electrons are negatively charged particles of atoms. All of the negatively charged electrons balance out all the positively charged protons in the atomic nucleus.

Ques. When a person combs their hair, static electricity is generated. Why?

Friction between the comb and hair transfers protons.
Friction between hair transfers electrons and the comb.
Contact between the hair and comb produces an electric charge.
Induction between hair and comb.

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Ans. (B) Friction between hair transfers electrons and the comb.

Explanation: Friction between the comb and hair transfers electrons because excess electrons accumulate on the comb and when you comb your hair, the plastic molecules

are close enough to capture and retain the electrons from the hair molecule.

Ques. Resistance is the measurement of a material’s opposition to______.

Electric current
Positively charged protons
Negatively charged neutrons
Electric flux

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Ans. (A) Electric current

Explanation: Resistance can be defined as the measure of the opposition to current flow in an electrical circuit. It is measured in ohms and is symbolized by the Greek letter Ω.

Read More: Ohm's Law and Its Limitations

Ques. What kind of material contains lots of free electrons?

Semiconductors
Insulators
Conductors
All of the above

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Ans. (C) Conductors

Explanation: Conductors are materials that allow electricity to flow through them. They conduct electricity by allowing electrons to flow inside them easily from atom to atom. Conductors have free electrons on their surface which allow current to pass through them easily.

Ques. When two negatively charged materials will be placed together, they will

They will repel each other
They will attract each other
They will become protons
None of the above

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Ans. (A) They will repel each other.

Explanation: In an electric field the direction of the field is decided by the electric charge of the charged material. All the electric fields begin on a positive charge and end on a negative charge. When two negatively charged materials are placed together, they will repel each other because their force is directed against each other.

Ques. When one resistor is removed from a circuit, the current

The current decreases.
The current decreases by half.
The current increases.
The current increases by half.

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Ans. (C) The current increases.

Explanation: When one resistor is removed from a circuit, the current increases because when the resistance decreases, the current increases. Current and resistance are inversely proportional to each other.

Ques. Combine three resistors 320 Ω, 450 Ω, and 600 Ω that are all in parallel. What is resistance?

142.57 ohms
1370 ohm
0.007 ohm
None of the above

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Ans. (A) 142.57 ohm

Explanation: 1/R = 1/R₁ + 1/R₂ + 1/R₃

1/R = 1/320 + 1/450 + 1/600

1/R = 101/14400

R = 142.57 ohm

Ques. What is the emf (electromotive force) of a car battery?

13 V
12 V
11 V
None of the above

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Ans. (B) 12 V

Explanation: Electromotive force (EMF) measures the force that is exerted on a charge when no current is flowing. The 12 V lead-storage battery consists of six cells. Each cell produces 2 V approximately.

Ques. 10 kWh is equal to ____ joules.

36000
360000
3600
36000000

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Ans. (D) 36000000

Explanation: 1 kWh = 3600000 Joules

Therefore, 10 kWh = 36000000 Joules

Ques. ______ is a heat-sensitive device whose resistivity changes with the change in temperature.

Thermometer
Thermistor
Resistor
Conductor

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Ans. (B) Thermistor

Explanation: A thermistor is a resistance thermometer. The thermistor word is formed from the combination of the word ‘thermal’ and ‘resistor’. There are two kinds of thermistors-

Negative temperature coefficient (NTC)- When temperature increases, resistance decreases.
Positive temperature coefficient (PTC)- When the temperature decreases, resistance increases.

Ques. If a metal wire is a constant potential difference. When the temperature of the wire increases, then the drift velocity of the electron in it-

Increases and the thermal velocity of the electrons decreases.
Decreases and the thermal velocity of the electron increases.
Increases, the thermal velocity of the proton in it increases.
Decreases and the thermal velocity of the proton in it decreases.

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Ans. (B) Decreases and the thermal velocity of the electron increases.

Explanation: The drift velocity of the electron in it decreases, and the thermal velocity of the electron increases because when the current density decreases the drift velocity decreases. When the temperature increases resistance also increases.

Ques. Nichrome is used for making filament for electric heaters because of

Low conductivity and small temperature coefficient of resistivity
High conductivity and small temperature coefficient of resistivity
High conductivity and Large temperature coefficient of resistivity
Low conductivity and Large temperature coefficient of resistivity

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Ans. (A) High conductivity and small temperature coefficient of resistivity

Explanation: Nichrome (an alloy of Nickel, Copper, and Chromium) has high resistivity, low conductivity, and a small temperature coefficient of resistivity.

Ques. What is the value of the Boltzmann Constant?

1.381 x 10^-23 J mole^-1 K^-1
2.56 x 10^-23 J mole^-1 K^-1
1.381 x 10^-26 J mole^-1 K^-1
3.381 x 10^-23 J mole^-1 K^-1

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Ans. (A) 1.381 x 10^-23 J mole^-1 K^-1

Explanation: The value of the Boltzmann constant is 1.381 x 10^-23 J mole^-1 K^-1 or 1.381 x 10^-23 m² kg s^-2 K^-1

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Current Electricity MCQs with Explanation

Current Electricity Detailed Video Explanation:

Here are some important MCQs on Current Electricity for the students to test and assess their knowledge on the given topic.

CBSE CLASS XII Related Questions

1.
What is displacement current (\( i_d \))? Considering the case of charging of a capacitor, show that \( i_d = \varepsilon_0 \frac{d\Phi_E}{dt} \). What is the value of \( i_d \) for a conductor across which a constant voltage is applied?

2.
The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

3.
Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

4.
Write any two features of nuclear forces.

5.
Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

6.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

Similar Physics Concepts

Comments

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Current Electricity MCQs with Explanation

Current Electricity Detailed Video Explanation:

Here are some important MCQs on Current Electricity for the students to test and assess their knowledge on the given topic.

CBSE CLASS XII Related Questions

1.What is displacement current (\( i_d \))? Considering the case of charging of a capacitor, show that \( i_d = \varepsilon_0 \frac{d\Phi_E}{dt} \). What is the value of \( i_d \) for a conductor across which a constant voltage is applied?

2.The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

3.Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

4. Write any two features of nuclear forces.

5.Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

6.Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
What is displacement current (\( i_d \))? Considering the case of charging of a capacitor, show that \( i_d = \varepsilon_0 \frac{d\Phi_E}{dt} \). What is the value of \( i_d \) for a conductor across which a constant voltage is applied?

2.
The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

3.
Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

4.
Write any two features of nuclear forces.

5.
Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

6.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))