Free Resistance and Resistivity MCQs with Answers
86 Resistance and Resistivity MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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- A. hyperbola
- B. ellipse
- C. parabola
- D. straight line
Explanation: Ohm's law is V = IR, so for constant resistance a graph of potential difference V in volts (V) against current I in amperes (A) is a…
Correct answer: straight line- A. 40 W bulb
- B. 60 W blub
- C. 100 W blub
- D. all will burn equally brightly
Explanation: At the same rated voltage of 220 V, each bulb's resistance is R = V²/P, so the 40 W bulb has the greatest resistance.
Correct answer: 40 W bulb- A. iron
- B. tungsten
- C. silver
- D. copper
Explanation: Copper is preferred for connecting wires because it has low resistivity, so it carries current with little energy loss, and it is much…
Correct answer: copper- A. finite
- B. infinite
- C. zero
- D. changes with every conductor
Explanation: Below its critical temperature, a superconductor allows charge to flow without resistance, so its resistance is zero ohm.
Correct answer: zero- A. remains the same
- B. is doubled
- C. is halved
- D. becomes zero
Explanation: Resistivity is a property of the material, represented by ρ in R = ρL/A, so cutting the wire changes its length and resistance but not its…
Correct answer: remains the same- A. nature of conductor
- B. dimension of conductor
- C. physical state of the conductor
- D. all of above
Explanation: Resistance follows R = ρL/A, so it depends on the conductor's dimensions and material, while resistivity can also change with physical…
Correct answer: all of above- A. constantan
- B. nichrome
- C. copper
- D. tungsten
Explanation: Tungsten is used for bulb filaments because it has a very high melting point and can become white-hot without melting.
Correct answer: tungsten- A. will depend on its length
- B. will depend on its radius
- C. will depend on the type of material of the wire
- D. will depend on none of the above
Explanation: Specific resistance, or resistivity, is an intrinsic property determined mainly by the material and its temperature, not by the wire's…
Correct answer: will depend on the type of material of the wire- A. 100W
- B. 200W
- C. 60W
- D. all
Explanation: At the same supply voltage, R = V²/P, so the 60 W bulb has the greatest resistance and therefore the smallest filament cross-sectional…
Correct answer: 200W- A. resistance
- B. inductance
- C. conductivity
- D. flexibility
Explanation: Conductivity is the reciprocal of resistivity, σ = 1/ρ, and its SI unit is siemens per metre.
Correct answer: conductivity- A. infinite
- B. zero
- C. finite
- D. depends upon nature
Explanation: An ideal insulator does not allow current to flow, which is represented by infinite resistance.
Correct answer: infinite- A. very good conductor
- B. moderately good conductor
- C. an insulator
- D. no specific criterion available
Explanation: Conductance is the reciprocal of resistance, G = 1/R, so a very high conductance means the wire offers very little opposition to current…
Correct answer: very good conductor- A. ML-1T-2
- B. ML-2T-2
- C. MLT-2
- D. ML2T-2
Explanation: Elastic modulus is stress divided by strain, and strain has no dimensions.
Correct answer: ML-1T-2- A. 2 ohm
- B. 3 ohm
- C. 2/3 ohm
- D. 3/2 ohm
Explanation: Since we have a uniform wire, therefore the resistance of each side of the triangle will be equal as the length of each is also equal.
Correct answer: 2/3 ohm- A. 2R
- B. 4R
- C. 8R
- D. 16R
Explanation: The resistance (R) of a wire is given by formula: R = ρ L/Awhere ( ρ ) is the resistivity of the material, ( L ) is the length of the…
Correct answer: 16R- A. Double
- B. Half
- C. four time
- D. Eight time
Explanation: When a wire with uniform cross-sectional area ( A ) and length ( L ) is cut into two equal parts, the resistance of each part becomes ( R'…
Correct answer: Half- A. Conductivity
- B. Conductance
- C. Resistance
- D. Resistivity
Explanation: The slope of the current-voltage (I-V) graph for a resistor is numerically equal to the reciprocal of the resistance (conductivity) (1/R)…
Correct answer: Conductivity- A. R/4
- B. 4R
- C. 16R
- D. R/2
Explanation: The resistance of a wire is given by the formula: R=ρL /Awhere:R is the resistance,ρ is the resistivity of the material,L is the length of…
Correct answer: 16R- A. Ω-m2
- B. (Ω-m)-1
- C. Ω-m
- D. (Ω-m)-2
Explanation: Resistivity (ρ) is a fundamental property of materials that quantifies how strongly a material opposes the flow of electric current.
Correct answer: Ω-m- A. 2.5 Ω.
- B. 5 Ω.
- C. 20 Ω.
- D. 40 Ω.
Explanation: 5 / 20 = 10 / R4To find R4, we can cross-multiply:5 * R4 = 20 * 105 * R4 = 200R4 = 200 / 5R4 = 40 ΩTherefore, the unknown resistance R4 is…
Correct answer: 40 Ω.