MCQ on Unit of Specific Resistance: Introduction & Explanation

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The SI unit of specific resistance is ohm meter (Ωm). Resistivity or specific resistance can be defined as the resistance offered per unit length and unit cross-sectional area when a known amount of voltage is applied. The mathematical representation of specific resistance is ρ = RA/L, where R is the conductor's resistance, L is the conductor's length, A is the conductor's cross-sectional area, and ρ is the material's proportionality constant, often called its specific resistance or resistivity.

Specific Resistance

Specific Resistance

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Current Electricity Detailed Video Explanation:

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Ques 1: The resistance of any conductor depends on the _____ factor.

length of substance
cross-sectional area
temperature & nature of the material
all are correct

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Ans: The correct answer is (4).

Explanation: The resistance of a conductor depends upon the resistivity, length, and cross-sectional area of the conductor which is represented by the relation (R=ρAl). It does also depend on other physical factors like temperature etc. Its SI unit is Ohm (Ω).

Ques 2: The conductor’s resistance is directly proportional to its length (R ∝ L).

True
False

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Ans: The correct option is (1) True.

Explanation: The resistance of a conductor is directly proportional to its length (L) as R ∝ L. This is the reason why doubling its length will double its resistance while halving its length would halve its resistance. Also, the resistance of a conductor is inversely proportional to its cross-sectional area (A) as R ∝ 1/A.

Ques 3: The resistance of a conductor is _________ proportional to its cross-sectional area of it.

Indirectly
Directly

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Ans: The correct option is (1) Indirectly

Explanation: When there is an increase in the area of cross-section the space between the charged particles increases, there will be a decrease in the probability of collision. Therefore, resistance decreases as the area increases. In other words, they are inversely proportional.

Ques 4: The rate of flow of electric charge through any cross-section of a conductor is called _________?

Electric flux
Electric current
Electric potential
Electric field

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Ans: The correct answer is (2) Electric current

Explanation: The rate of flow of electric charges through a conductor is referred to as electric current. The electric current flowing through a conductor is often defined as the quantity of electric charge following across the cross-section of the conductor in one second.

Ques 5: Which among the following is non-ohmic resistance?

Carbon resistor
Diode
Lamp filament
Copper wire

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Ans: The correct answer is (2) Diode is non-ohmic resistance.

Explanation: A non-ohmic resistance is a resistance that does not follow Ohm’s law which states that the current through a conductor between two points is directly proportional to the voltage across the two points. The main Characteristic of Ohmic resistance is the VI curve which is a straight line, and the diode does not have a straight line as a VI curve.

Ques 6: Current density is a _______?

Scalar
Vector
Dimensionless quantity
None of the options

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Ans: The correct answer is (2) vector.

Explanation: Current density is a vector quantity because it is a product of charge density and velocity. Here charge density is a scalar quantity, and velocity is a vector quantity, which makes current density also a vector quantity.

Ques 7: The resistivity of certain metals or alloys reduces to zero when they are cooled below a certain temperature, this phenomenon is known as _________?

Conductivity
Partial conductivity
Superconductivity
Non-conductivity

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Ans: The correct option is (3) Superconductivity

Explanation: The resistivity of certain metals or alloys reduces to zero when they are cooled below a certain temperature, this phenomenon is known as superconductivity.

Read Also: Electric Current

Ques 8: __________ is a constant factor that depends on the nature of conductor material.

Length
Area
Rho
Resistance

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Ans: The correct option is (3) Rho.

Explanation: Rho is specific resistance that remains invariable for particular metal or conductor. In an ohmic conductor, resistance increases with an increase in temperature increases because the thermal velocity of the free electrons increases as the temperature increases. This results in an increase in the number of collisions between the free electrons.

Ques 9: The Rho (∝) is also called specific resistance or resistivity.

True
False

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Ans: The correct option is (1) True.

Explanation: Resistance is inversely proportional to the area of the conductor. Where ϱ (Rho) is constant for the material known as its specific resistance or resistivity. "The Specific resistance of a material is the resistance of a piece of unit length and unit cross-sectional area."

Ques 10: The total resistance in the series combination is more than the greatest resistance in the circuit.

True
False

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Ans: The correct option is (a) True

Explanation: The total resistance in the series combination is more than the greatest resistance in the circuit.

Ques 11: What happens with the requirement of Power rating when the resistance increases?

Lower Power Rating
Higher Power Rating

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Ans: The correct answer is (1)

Explanation: Resistors oppose the current so they will dissipate some power. According to this equation, V²/R = P = I²⋅R, power is inversely proportional to resistance on the left side and directly proportional to resistance on the right side. So power rating is important in such a way that dissipated power should be lower than the power rating of the resistor.

Ques 12: Resistors are ________________ devices.

Polarity Devices
Non-Polarity

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Ans: The correct answer is (2) Non-Polarity.

Explanation: The resistance does not have polarity because it opposes the flow of electrons. The flow of electrons is from the lower potential to the higher potential. However, if the resistor is not intrinsic, if or has impurities changing its resistance throughout the length then there occurs a difference in the V-I characteristics of the resistor.

Ques 13: Most common type of Resistor is _________________________?

Film Type Resistor
Carbon Resistor
Wire Wound Resistor
Fusible Resistor

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Ans: The correct answer is (2) Carbon Resistor.

Explanation: Carbon resistor types are very cheap to make which is why commonly used in electrical circuits. However, due to their manufacturing process carbon-type resistors have very large tolerances so for more precision and high-value resistances, film-type resistors are used instead.

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MCQ on Unit of Specific Resistance: Introduction & Explanation

Current Electricity Detailed Video Explanation:

CBSE CLASS XII Related Questions

2.
Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

3.
Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.
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: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5.
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:

6.
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?

Similar Physics Concepts

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MCQ on Unit of Specific Resistance: Introduction & Explanation

Current Electricity Detailed Video Explanation:

CBSE CLASS XII Related Questions

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

3.Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.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: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5.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:

6.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?

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

2.
Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

3.
Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.
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: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5.
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:

6.
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?