Q.1 Which metal has the highest electrical conductivity at room temperature?
Copper
Silver
Aluminum
Gold
Explanation - Silver has the highest electrical conductivity (~59 × 10^6 S/m) among common metals, slightly surpassing copper.
Correct answer is: Silver
Q.2 What is the primary property that makes copper a good electrical conductor?
High melting point
Low resistivity
High tensile strength
Magnetic permeability
Explanation - Copper has a low resistivity (1.68 × 10^−8 Ω·m), allowing electrons to flow easily, which makes it a good conductor.
Correct answer is: Low resistivity
Q.3 Which factor decreases the electrical resistance of a conductor when temperature is lowered?
Decrease in cross‑sectional area
Increase in electron scattering
Decrease in electron scattering
Increase in lattice vibrations
Explanation - Lower temperatures reduce lattice vibrations, decreasing electron scattering and thus resistance.
Correct answer is: Decrease in electron scattering
Q.4 Why is copper preferred over aluminium in most power transmission cables?
Higher conductivity and lower cost
Higher conductivity but higher cost
Lower conductivity and higher cost
Lower conductivity but lower cost
Explanation - Copper has higher conductivity and is more expensive, yet it provides better performance per cost for many applications.
Correct answer is: Higher conductivity but higher cost
Q.5 Which of the following is NOT a common characteristic of good conductors?
High electron mobility
Large band gap
Low resistivity
High thermal conductivity
Explanation - Good conductors have small or zero band gaps; a large band gap is characteristic of insulators.
Correct answer is: Large band gap
Q.6 What does the term 'resistivity' refer to in a conductor?
The amount of resistance per unit length
The resistance per unit volume
The resistance per unit cross‑sectional area per unit length
The resistance at a given temperature
Explanation - Resistivity is defined as R = ρL/A, where ρ is the resistivity, L the length, and A the cross‑section.
Correct answer is: The resistance per unit cross‑sectional area per unit length
Q.7 Which material is commonly used as a conductor in high‑frequency applications?
Copper
Silver
Gold
Aluminium
Explanation - Silver's very low resistivity and minimal skin effect make it ideal for high‑frequency signals.
Correct answer is: Silver
Q.8 The resistance of a copper wire doubles if its temperature is increased from 20 °C to approximately what temperature?
70 °C
120 °C
200 °C
300 °C
Explanation - Copper's temperature coefficient of resistance is about 0.0039 /°C; resistance doubles at ~120 °C from 20 °C.
Correct answer is: 120 °C
Q.9 Which of the following is an advantage of using copper alloys like brass as conductors?
Higher electrical conductivity
Increased mechanical strength
Lower cost
Higher thermal conductivity
Explanation - Alloys like brass improve mechanical strength and corrosion resistance at a moderate cost in trade‑off for slightly lower conductivity.
Correct answer is: Increased mechanical strength
Q.10 Why does gold have a lower resistivity compared to aluminium?
Gold has a higher atomic number
Gold has more free electrons
Gold has a higher melting point
Gold has a lower density
Explanation - Gold's electronic structure allows for more conduction electrons, reducing resistivity relative to aluminium.
Correct answer is: Gold has more free electrons
Q.11 Which law relates the voltage, current, and resistance in a simple circuit?
Ohm's Law
Faraday's Law
Kirchhoff's Voltage Law
Lenz's Law
Explanation - Ohm's Law states V = IR, connecting voltage (V), current (I), and resistance (R).
Correct answer is: Ohm's Law
Q.12 In a conductor, what primarily determines its electrical resistance?
Number of atoms
Electron mean free path
Melting point
Magnetic properties
Explanation - Resistance depends on how far electrons travel before scattering; shorter mean free paths increase resistance.
Correct answer is: Electron mean free path
Q.13 What is the 'skin effect' in conductors?
Increased resistance at low temperatures
Current concentrating near the surface at high frequencies
Conductivity decreasing with temperature
Magnetic field penetration through the conductor
Explanation - At high frequencies, alternating current tends to flow near the surface, reducing effective cross‑sectional area.
Correct answer is: Current concentrating near the surface at high frequencies
Q.14 Which of the following materials is NOT used as a conductor in power systems?
Copper
Silver
Lead
Aluminium
Explanation - Lead is a poor conductor with high resistivity and is not used in power transmission.
Correct answer is: Lead
Q.15 What is the typical resistivity of aluminium at 20 °C?
2.82 × 10^−8 Ω·m
1.68 × 10^−8 Ω·m
5.00 × 10^−8 Ω·m
7.14 × 10^−8 Ω·m
Explanation - Aluminium’s resistivity is about 2.82 × 10^−8 Ω·m, higher than copper but still low.
Correct answer is: 2.82 × 10^−8 Ω·m
Q.16 Which factor does NOT affect the resistivity of a conductor?
Temperature
Material composition
Applied voltage
Impurity content
Explanation - Resistivity is independent of applied voltage; it depends on material, temperature, and impurities.
Correct answer is: Applied voltage
Q.17 Which alloy is known for combining high conductivity with excellent corrosion resistance?
Copper‑tin
Copper‑zinc
Copper‑nickel
Copper‑silver
Explanation - Copper‑tin (copper–tin alloy) offers good conductivity and is widely used in connectors and terminals.
Correct answer is: Copper‑tin
Q.18 What is the primary reason for using gold plating on connectors?
Higher conductivity
Corrosion resistance
Lower cost
Magnetic shielding
Explanation - Gold plating prevents oxidation, maintaining good electrical contact over time, especially in harsh environments.
Correct answer is: Corrosion resistance
Q.19 Which of the following is a correct statement about resistivity?
It increases with temperature for metals
It decreases with temperature for metals
It is constant for all conductors
It is measured in ohms per meter
Explanation - Metals become less conductive as temperature rises, leading to higher resistivity.
Correct answer is: It increases with temperature for metals
Q.20 Which of the following best describes the 'mean free path' of an electron?
The average distance between collisions
The average time between collisions
The average energy of electrons
The average number of electrons per atom
Explanation - Mean free path is the distance electrons travel before scattering.
Correct answer is: The average distance between collisions
Q.21 In which of the following applications is a silver alloy most commonly used?
Power transmission lines
High‑frequency RF connectors
Low‑temperature cryogenic cables
Automotive battery terminals
Explanation - Silver’s low resistivity makes it ideal for RF connectors and high‑speed digital interconnects.
Correct answer is: High‑frequency RF connectors
Q.22 What does the 'temperature coefficient of resistance' (TCR) describe?
Change in resistance with applied voltage
Change in resistance with frequency
Change in resistance with temperature
Change in resistance with pressure
Explanation - TCR quantifies how much a material’s resistance changes per degree of temperature change.
Correct answer is: Change in resistance with temperature
Q.23 Which of these conductors has the lowest melting point?
Copper
Aluminium
Lead
Silver
Explanation - Lead melts at 327 °C, significantly lower than the other listed metals.
Correct answer is: Lead
Q.24 In the context of electrical conductors, what is 'specific resistance'?
Resistance per unit length
Resistance per unit cross‑sectional area
Resistance per unit volume
Resistance per unit mass
Explanation - Specific resistance (resistivity) is resistance per unit length per unit area, typically expressed in Ω·m.
Correct answer is: Resistance per unit length
Q.25 Which of the following is a direct consequence of high electrical conductivity?
Higher power loss
Lower power loss
Higher heat generation
Lower voltage drop
Explanation - High conductivity means low resistance, leading to reduced Joule heating and power loss.
Correct answer is: Lower power loss
Q.26 Which of the following materials is considered a semiconductor?
Copper
Gold
Silicon
Aluminium
Explanation - Silicon has a band gap and is the most widely used semiconductor material.
Correct answer is: Silicon
Q.27 Which property is NOT directly related to a conductor’s ability to transfer heat?
Electrical conductivity
Thermal conductivity
Specific heat
Electrical resistivity
Explanation - Specific heat measures heat capacity, not transfer; conductivity and resistivity are related via Wiedemann–Franz law.
Correct answer is: Specific heat
Q.28 Which of the following metals has the highest melting point?
Tungsten
Copper
Lead
Gold
Explanation - Tungsten melts at 3422 °C, the highest among common metals.
Correct answer is: Tungsten
Q.29 In which scenario is aluminium preferred over copper for cable manufacturing?
When maximum conductivity is required
When weight savings are critical
When the environment is corrosive
When cost is not a concern
Explanation - Aluminium is lighter than copper, making it suitable for weight‑sensitive applications like aerospace.
Correct answer is: When weight savings are critical
Q.30 Which of the following is a typical use of copper‑nickel alloys?
Marine battery terminals
High‑temperature furnaces
Low‑temperature cryogenic lines
Optical fibers
Explanation - Copper‑nickel resists corrosion in saltwater environments, ideal for marine applications.
Correct answer is: Marine battery terminals
Q.31 Which statement about resistivity and conductivity is true?
Resistivity is the inverse of conductivity
Conductivity is the inverse of resistivity
Both are directly proportional
They are unrelated
Explanation - σ = 1/ρ, where σ is conductivity and ρ is resistivity.
Correct answer is: Conductivity is the inverse of resistivity
Q.32 Which of these factors has the greatest impact on the resistance of a wire at room temperature?
Length
Cross‑sectional area
Material resistivity
Ambient temperature
Explanation - Material resistivity is an intrinsic property and dominates resistance compared to geometry at a fixed temperature.
Correct answer is: Material resistivity
Q.33 Which of the following is a typical application of a conductive polymer?
Electrical wiring
Flexible printed circuit boards
High‑voltage insulators
Static shielding
Explanation - Conductive polymers allow flexible, lightweight interconnects in flexible electronics.
Correct answer is: Flexible printed circuit boards
Q.34 What is the main disadvantage of using silver as a bulk conductor?
Low conductivity
High cost
Corrosiveness
High density
Explanation - Silver is expensive; thus, it is generally used in plated form or in small quantities.
Correct answer is: High cost
Q.35 Which of the following metals has the lowest density among common conductors?
Copper
Aluminium
Silver
Gold
Explanation - Aluminium has a density of 2.70 g/cm³, lower than the others.
Correct answer is: Aluminium
Q.36 Which property of a conductor determines how much it will expand when heated?
Thermal expansion coefficient
Thermal conductivity
Electrical resistivity
Magnetic permeability
Explanation - Thermal expansion coefficient quantifies linear expansion per degree temperature change.
Correct answer is: Thermal expansion coefficient
Q.37 What is the main cause of increased resistance in a conductor over time?
Oxidation
Cooling
Mechanical stress
Low temperature
Explanation - Oxidation forms non‑conductive layers, increasing resistance.
Correct answer is: Oxidation
Q.38 Which of the following is a characteristic of a good conductor at very low temperatures?
High resistivity
Superconductivity
Large band gap
High magnetic susceptibility
Explanation - Some materials become superconductors (zero resistance) below critical temperatures.
Correct answer is: Superconductivity
Q.39 Which alloy is commonly used for high‑current busbars in power distribution?
Copper‑tin
Copper‑nickel
Aluminium‑silicon
Lead‑tin
Explanation - Copper‑tin alloys have good conductivity and mechanical strength for busbar applications.
Correct answer is: Copper‑tin
Q.40 Which of the following is true regarding the skin depth in a conductor?
It increases with frequency
It decreases with frequency
It is independent of conductivity
It is the same as the conductor's diameter
Explanation - Higher frequencies cause the current to concentrate closer to the surface, reducing skin depth.
Correct answer is: It decreases with frequency
Q.41 Which metal is most commonly used for busbars in industrial control panels?
Copper
Silver
Lead
Gold
Explanation - Copper offers excellent conductivity and mechanical durability for busbars.
Correct answer is: Copper
Q.42 Which of the following is a primary reason for using copper in power cables?
High electrical resistance
Low cost
High tensile strength
Low density
Explanation - Copper balances conductivity, mechanical properties, and cost, making it economical for large‑scale power cables.
Correct answer is: Low cost
Q.43 What does 'electrical resistivity' depend on?
Temperature and material purity
Magnetic field strength
Frequency of current
Ambient pressure
Explanation - Resistivity varies with temperature and the presence of impurities or defects.
Correct answer is: Temperature and material purity
Q.44 Which of the following metals has the lowest electrical resistivity at room temperature?
Silver
Copper
Aluminium
Gold
Explanation - Silver’s resistivity (~1.59 × 10^−8 Ω·m) is lower than that of copper.
Correct answer is: Silver
Q.45 What is the effect of increasing current on the temperature of a copper wire?
It decreases temperature
It has no effect
It increases temperature due to Joule heating
It increases temperature linearly with current
Explanation - Higher current leads to more resistive heating (P = I²R), raising the wire’s temperature.
Correct answer is: It increases temperature due to Joule heating
Q.46 Which material property is directly measured in ohm‑meter (Ω·m)?
Electrical resistivity
Conductivity
Resistance
Voltage
Explanation - Resistivity is expressed as Ω·m, representing resistance per unit length and cross‑sectional area.
Correct answer is: Electrical resistivity
Q.47 Which of the following is a major advantage of using silver in RF applications?
Low cost
High magnetic permeability
Lowest resistivity
High thermal expansion
Explanation - Silver’s lowest resistivity reduces skin‑effect losses in high‑frequency circuits.
Correct answer is: Lowest resistivity
Q.48 Which of these materials is considered a good conductor for high‑temperature applications?
Aluminium
Copper
Nickel
Iron
Explanation - Nickel maintains conductivity at higher temperatures compared to copper and aluminium.
Correct answer is: Nickel
Q.49 Why is aluminium less conductive than copper despite being lighter?
Higher resistivity
Higher density
Lower melting point
Lower thermal expansion
Explanation - Aluminium has a higher resistivity (~2.82 × 10^−8 Ω·m) than copper, reducing conductivity.
Correct answer is: Higher resistivity
Q.50 Which of the following is NOT a factor that influences the skin depth in a conductor?
Frequency
Conductivity
Temperature
Magnetic permeability
Explanation - Skin depth primarily depends on frequency, conductivity, and magnetic permeability, not directly on temperature.
Correct answer is: Temperature
Q.51 What is the primary reason for using copper over aluminium in high‑frequency coaxial cables?
Higher resistivity
Lower attenuation
Higher cost
Higher dielectric constant
Explanation - Copper’s lower resistivity reduces signal loss in high‑frequency coaxial cables.
Correct answer is: Lower attenuation
Q.52 Which property of a conductor determines its ability to conduct heat efficiently?
Electrical conductivity
Electrical resistivity
Thermal conductivity
Specific heat
Explanation - Thermal conductivity measures heat transfer; high values indicate good heat conduction.
Correct answer is: Thermal conductivity
Q.53 Which of the following metals is not used as a conductor in electrical circuits?
Copper
Lead
Titanium
Aluminium
Explanation - Titanium has high resistivity and is not commonly used as a conductor.
Correct answer is: Titanium
Q.54 What is the typical value of the temperature coefficient of resistance for copper?
0.0018 /°C
0.0039 /°C
0.0050 /°C
0.0071 /°C
Explanation - Copper’s TCR is ~0.0039 /°C, indicating a moderate increase in resistance with temperature.
Correct answer is: 0.0039 /°C
Q.55 Which of the following is the best way to reduce skin effect in high‑frequency conductors?
Use thicker wires
Use high‑temperature alloys
Use hollow conductors
Use high‑purity metals
Explanation - Hollow conductors allow current to flow primarily near the surface, mitigating skin‑effect losses.
Correct answer is: Use hollow conductors
Q.56 Which of these metals is used for its high resistance to corrosion in marine environments?
Copper‑tin
Copper‑nickel
Aluminium‑silicon
Lead‑tin
Explanation - Copper‑nickel resists corrosion in saltwater, making it ideal for marine applications.
Correct answer is: Copper‑nickel
Q.57 Which factor does not affect the resistivity of a conductor?
Material composition
Impurities
Electric field strength
Temperature
Explanation - Resistivity depends on material properties and temperature, not directly on electric field.
Correct answer is: Electric field strength
Q.58 Which of the following is true about superconductors?
They have high resistivity at low temperatures
They exhibit zero resistance below a critical temperature
They are made of pure silver
They are only used at high temperatures
Explanation - Superconductors lose all electrical resistance when cooled below their critical temperature.
Correct answer is: They exhibit zero resistance below a critical temperature
Q.59 What is the effect of increasing the cross‑sectional area of a conductor?
Increases resistance
Decreases resistance
Increases resistivity
Decreases resistivity
Explanation - Resistance is inversely proportional to cross‑sectional area (R = ρL/A).
Correct answer is: Decreases resistance
Q.60 Which metal has the lowest density among the top four conductors?
Silver
Copper
Aluminium
Gold
Explanation - Aluminium’s density is about 2.70 g/cm³, lower than the others.
Correct answer is: Aluminium
Q.61 Which property of a conductor determines how easily electrons can move through it?
Resistivity
Conductivity
Density
Melting point
Explanation - Higher conductivity means electrons can move more freely through the material.
Correct answer is: Conductivity
Q.62 Which of the following materials is commonly used as a conductive ink in printed electronics?
Graphene
Silicon
Quartz
Ceramic
Explanation - Graphene has high conductivity and can be dispersed in inks for flexible circuits.
Correct answer is: Graphene
Q.63 What is the main reason for gold plating on electrical connectors?
Higher conductivity
Corrosion resistance
Higher melting point
Magnetic shielding
Explanation - Gold does not oxidize, maintaining a clean conductive surface over time.
Correct answer is: Corrosion resistance
Q.64 Which property is increased in a conductor when its temperature is raised?
Conductivity
Resistivity
Cross‑sectional area
Length
Explanation - Higher temperatures increase lattice vibrations, raising resistivity.
Correct answer is: Resistivity
Q.65 Which of the following metals has the highest melting point?
Tungsten
Copper
Gold
Silver
Explanation - Tungsten melts at 3422 °C, the highest among common metals.
Correct answer is: Tungsten
Q.66 What does the 'skin effect' cause in high‑frequency AC circuits?
Increased effective resistance
Decreased power loss
Increased magnetic field
Decreased temperature rise
Explanation - Current concentrates near the surface, reducing effective area and increasing resistance.
Correct answer is: Increased effective resistance
Q.67 Which of the following is true for a conductor used in a high‑temperature environment?
It must have low electrical resistivity
It must be highly magnetic
It should have high thermal expansion
It should be made of a superconductor
Explanation - Low resistivity ensures efficient power delivery even when temperatures are high.
Correct answer is: It must have low electrical resistivity
Q.68 Which of the following metals is commonly used as a conductor in radio‑frequency (RF) antennas?
Silver
Lead
Titanium
Bismuth
Explanation - Silver’s low resistivity and excellent RF properties make it ideal for antennas.
Correct answer is: Silver
Q.69 Which factor directly influences the resistivity of a metal?
Magnetic field
Lattice structure
Current amplitude
Voltage magnitude
Explanation - The atomic arrangement and defects in the lattice affect electron scattering, impacting resistivity.
Correct answer is: Lattice structure
Q.70 Which of the following materials is a good conductor and also has excellent resistance to oxidation?
Copper
Nickel
Iron
Lead
Explanation - Nickel resists oxidation and maintains conductivity in oxidizing environments.
Correct answer is: Nickel
Q.71 Which of the following is a key property of a conductor used in cryogenic applications?
Superconductivity
High resistivity
Low thermal expansion
High magnetic permeability
Explanation - Superconductors allow loss‑free current flow at low temperatures.
Correct answer is: Superconductivity
Q.72 Which of the following materials is used as a conductor in high‑frequency printed circuit boards due to its low dielectric loss?
Copper
Aluminium
Silver
Gold
Explanation - Silver has minimal dielectric losses, preserving signal integrity at high frequencies.
Correct answer is: Silver
Q.73 Which factor determines how quickly a conductor heats up under current flow?
Resistivity
Melting point
Density
Electrical capacitance
Explanation - Higher resistivity causes more Joule heating (P = I²R), raising the temperature faster.
Correct answer is: Resistivity
Q.74 Which of the following is NOT a typical application of copper?
Electrical wiring
Heat sinks
High‑temperature furnaces
Grounding straps
Explanation - Copper oxidizes at high temperatures, making it unsuitable for high‑temperature furnaces.
Correct answer is: High‑temperature furnaces
Q.75 Which metal has the highest electrical resistance among common metals?
Lead
Silver
Copper
Aluminium
Explanation - Lead has a high resistivity (~2.44 × 10^−7 Ω·m), making it a poor conductor.
Correct answer is: Lead
Q.76 What is the main advantage of using a copper alloy like cupronickel in electrical contacts?
Higher electrical conductivity
Improved corrosion resistance
Lower cost
Higher melting point
Explanation - Cupronickel resists corrosion while maintaining acceptable conductivity.
Correct answer is: Improved corrosion resistance
Q.77 Which of these properties does not improve with increased purity of a metal conductor?
Conductivity
Melting point
Resistivity
Electrical noise
Explanation - Higher purity reduces impurities that cause noise, so purity generally decreases noise, not improves.
Correct answer is: Electrical noise
Q.78 Which metal is commonly used for high‑current busbars because of its low resistivity and high strength?
Copper‑tin
Copper‑nickel
Aluminium‑silicon
Lead‑tin
Explanation - Copper‑tin alloys provide both low resistivity and high mechanical strength.
Correct answer is: Copper‑tin
Q.79 Which of the following is a direct consequence of high electrical conductivity in a material?
Large heat generation
Low power loss
High resistivity
Low thermal conductivity
Explanation - High conductivity (low resistance) results in reduced Joule heating and power loss.
Correct answer is: Low power loss
Q.80 What is the primary reason for the use of copper in household wiring?
Low cost
High resistivity
High density
High magnetic permeability
Explanation - Copper provides a good balance between conductivity and cost for domestic wiring.
Correct answer is: Low cost
Q.81 Which of the following metals has the lowest resistivity at 0 °C?
Silver
Gold
Copper
Aluminium
Explanation - Silver’s resistivity at 0 °C (~1.59 × 10^−8 Ω·m) is the lowest among common metals.
Correct answer is: Silver
Q.82 Which property of a conductor determines the magnitude of the skin effect at a given frequency?
Resistivity
Conductivity
Magnetic permeability
All of the above
Explanation - Skin depth depends on resistivity, conductivity, and magnetic permeability.
Correct answer is: All of the above
Q.83 Which of the following is a typical application of aluminium conductors?
Power transmission lines
High‑frequency RF connectors
Cryogenic wiring
Magnetic shielding
Explanation - Aluminium is lightweight and sufficiently conductive for high‑voltage power lines.
Correct answer is: Power transmission lines
Q.84 Which of the following properties is NOT influenced by the electron‑phonon interaction?
Electrical resistivity
Thermal conductivity
Magnetic permeability
Heat capacity
Explanation - Electron‑phonon scattering mainly affects resistivity and thermal conductivity, not magnetic permeability.
Correct answer is: Magnetic permeability
Q.85 Which metal has the lowest density among the four main conductors (copper, silver, gold, aluminium)?
Silver
Copper
Gold
Aluminium
Explanation - Aluminium’s density (~2.70 g/cm³) is lower than that of copper, silver, and gold.
Correct answer is: Aluminium
Q.86 Which factor causes a conductor to experience increased resistance when the current density is very high?
Joule heating
Magnetic field generation
Electric field screening
Thermal expansion
Explanation - High current density produces significant Joule heating, raising temperature and resistance.
Correct answer is: Joule heating
Q.87 Which of the following is a key advantage of using copper for power cables?
High magnetic permeability
Low resistivity
Low density
High melting point
Explanation - Copper’s low resistivity makes it efficient for delivering power with minimal losses.
Correct answer is: Low resistivity
Q.88 Which of the following best describes the relationship between current density and skin depth?
Directly proportional
Inverse proportion
Independent
Square root dependence
Explanation - Higher current density increases the magnetic field, reducing skin depth.
Correct answer is: Inverse proportion
Q.89 Which of the following conductors is known for its excellent magnetic shielding properties?
Copper
Silver
Aluminium
Nickel
Explanation - Nickel has high magnetic permeability, making it useful for shielding.
Correct answer is: Nickel
Q.90 Which of the following metals is a good conductor and also has a high melting point suitable for high‑temperature environments?
Copper
Aluminium
Tungsten
Lead
Explanation - Tungsten’s high melting point (~3422 °C) and reasonable conductivity make it suitable for high‑temperature conductors.
Correct answer is: Tungsten
Q.91 Which of these metals is the most expensive per kilogram but has the highest conductivity?
Copper
Gold
Silver
Aluminium
Explanation - Gold is expensive but provides excellent conductivity and corrosion resistance.
Correct answer is: Gold
Q.92 What is the primary cause of the increase in resistance of a copper wire when it is heated to 200 °C?
Oxidation
Electron–phonon scattering
Magnetic field induction
Chemical reaction with air
Explanation - Higher temperature increases lattice vibrations, causing more electron scattering and higher resistance.
Correct answer is: Electron–phonon scattering
Q.93 Which of the following metals is commonly used as a conductor in high‑temperature superconducting magnets?
Copper
Aluminium
Nickel
Titanium
Explanation - Titanium alloys can support superconducting coils at high temperatures while providing mechanical support.
Correct answer is: Titanium
Q.94 Which property of a conductor determines its ability to dissipate heat generated by Joule heating?
Electrical resistivity
Thermal conductivity
Electrical conductivity
Specific heat
Explanation - High thermal conductivity allows efficient heat dissipation, preventing overheating.
Correct answer is: Thermal conductivity
Q.95 Which of the following is the best way to reduce resistive losses in a power transmission line?
Use a thicker conductor
Use a lower‑temperature conductor
Use a material with higher resistivity
Use a shorter conductor
Explanation - Increasing cross‑sectional area reduces resistance and thus power loss.
Correct answer is: Use a thicker conductor
Q.96 Which of these materials is known for its excellent electrical conductivity and also its high density?
Silver
Gold
Copper
Aluminium
Explanation - Gold has good conductivity and a high density, but its cost limits widespread use.
Correct answer is: Gold
Q.97 What is the effect of increasing the temperature on the resistance of a pure metal conductor?
Resistance decreases
Resistance remains the same
Resistance increases
Resistance oscillates
Explanation - Higher temperatures increase lattice vibrations, causing more electron scattering and higher resistance.
Correct answer is: Resistance increases
Q.98 Which property of a conductor is most directly measured in ohms per meter (Ω·m)?
Electrical conductivity
Electrical resistivity
Electrical resistance
Electrical capacitance
Explanation - Resistivity is expressed in Ω·m and represents intrinsic resistance per unit length and area.
Correct answer is: Electrical resistivity
Q.99 Which metal is widely used in high‑frequency interconnects due to its low resistivity and high thermal conductivity?
Copper
Aluminium
Silver
Nickel
Explanation - Silver’s low resistivity and good thermal conductivity make it ideal for high‑frequency interconnects.
Correct answer is: Silver
Q.100 Which of the following is a direct consequence of the skin effect on AC current?
Lower effective resistance
Higher effective resistance
No change in resistance
Reduced current density near the surface
Explanation - AC current flows near the surface, reducing effective cross‑sectional area and increasing resistance.
Correct answer is: Higher effective resistance
Q.101 Which of the following metals is commonly used for busbars due to its combination of low resistivity and high mechanical strength?
Copper‑tin
Copper‑nickel
Aluminium‑silicon
Lead‑tin
Explanation - Copper‑tin alloys provide low resistivity and good strength for busbar applications.
Correct answer is: Copper‑tin
Q.102 Which of the following is not a factor that influences the skin depth in a conductor?
Frequency of the AC signal
Electrical resistivity
Magnetic permeability
Current amplitude
Explanation - Skin depth depends on frequency, resistivity, and magnetic permeability, not on current amplitude.
Correct answer is: Current amplitude
Q.103 Which of the following materials is typically used as a conductor for high‑temperature electric heaters?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.104 What is the main reason for using gold plating on electrical contacts in harsh environments?
High conductivity
Corrosion resistance
Low cost
High magnetic permeability
Explanation - Gold does not oxidize, maintaining good electrical contact in corrosive conditions.
Correct answer is: Corrosion resistance
Q.105 Which of the following is a typical property of a good conductor at room temperature?
High resistivity
High electrical conductivity
Low thermal conductivity
High magnetic permeability
Explanation - Good conductors have low resistivity and high conductivity.
Correct answer is: High electrical conductivity
Q.106 Which metal has the lowest density among the most common conductors?
Silver
Copper
Aluminium
Gold
Explanation - Aluminium’s density (~2.70 g/cm³) is lower than that of copper, silver, and gold.
Correct answer is: Aluminium
Q.107 Which of the following is true regarding the temperature coefficient of resistance for aluminium?
It is negative
It is zero
It is positive and moderate
It is very high
Explanation - Aluminium’s TCR (~2.8 × 10^−3 /°C) indicates a moderate increase in resistance with temperature.
Correct answer is: It is positive and moderate
Q.108 Which of the following is a major advantage of using copper in high‑power distribution lines?
High resistivity
Low cost
High density
Low thermal conductivity
Explanation - Copper offers a good balance between cost and performance for power distribution.
Correct answer is: Low cost
Q.109 Which of the following metals is the most corrosion‑resistant among common conductors?
Silver
Gold
Copper
Aluminium
Explanation - Gold does not oxidize, giving it the highest corrosion resistance.
Correct answer is: Gold
Q.110 Which property of a conductor determines the maximum current it can carry before overheating?
Resistivity
Cross‑sectional area
Conductivity
Melting point
Explanation - A larger area reduces resistance and heat generation, allowing higher currents.
Correct answer is: Cross‑sectional area
Q.111 Which of the following metals is commonly used as a conductor in high‑frequency PCBs due to its low dielectric loss?
Copper
Aluminium
Silver
Gold
Explanation - Silver has minimal dielectric loss, preserving signal integrity at high frequencies.
Correct answer is: Silver
Q.112 Which factor does not affect the resistivity of a metal conductor?
Temperature
Purity
Magnetic field
Current density
Explanation - Resistivity is intrinsic and depends on temperature, purity, and magnetic field, not on current density.
Correct answer is: Current density
Q.113 Which of the following metals is NOT commonly used as a conductor in power distribution?
Copper
Aluminium
Lead
Silver
Explanation - Lead’s high resistivity makes it unsuitable for power distribution.
Correct answer is: Lead
Q.114 Which metal has the highest electrical conductivity among common metals?
Silver
Copper
Gold
Aluminium
Explanation - Silver’s conductivity is the highest due to its low resistivity.
Correct answer is: Silver
Q.115 Which of the following properties is a direct consequence of the electron mean free path?
Electrical resistivity
Thermal conductivity
Magnetic susceptibility
Melting point
Explanation - Shorter mean free paths increase resistivity.
Correct answer is: Electrical resistivity
Q.116 Which of the following conductors is most suitable for cryogenic applications?
Copper
Aluminium
Silver
High‑temperature superconductor
Explanation - Superconductors have zero resistance at cryogenic temperatures.
Correct answer is: High‑temperature superconductor
Q.117 What is the primary reason for using copper over aluminium in household wiring?
Higher resistivity
Higher cost
Better conductivity
Higher density
Explanation - Copper offers higher conductivity than aluminium, resulting in lower losses for the same current.
Correct answer is: Better conductivity
Q.118 Which of the following metals is NOT used as a conductor for high‑frequency RF circuits?
Silver
Gold
Copper
Lead
Explanation - Lead’s high resistivity makes it unsuitable for RF circuits.
Correct answer is: Lead
Q.119 Which property of a conductor determines its ability to withstand high temperatures without losing conductivity?
Thermal conductivity
Resistivity
Melting point
Density
Explanation - Higher melting points allow conductors to function at higher temperatures.
Correct answer is: Melting point
Q.120 Which of the following materials is often used as a conductive coating for flexible displays?
Graphene
Silicon
Quartz
Ceramic
Explanation - Graphene’s high conductivity and flexibility make it ideal for flexible electronics.
Correct answer is: Graphene
Q.121 Which of the following is NOT a typical characteristic of a good conductor?
Low resistivity
High electron mobility
High band gap
High thermal conductivity
Explanation - Good conductors have small or zero band gaps; a high band gap indicates an insulator.
Correct answer is: High band gap
Q.122 Which of the following metals is used as a conductor in high‑frequency coaxial cables because of its low loss tangent?
Copper
Aluminium
Silver
Nickel
Explanation - Silver provides the lowest loss tangent for high‑frequency applications.
Correct answer is: Silver
Q.123 Which of the following is a direct consequence of using a higher purity metal in a conductor?
Higher resistivity
Lower conductivity
Lower electron scattering
Higher melting point
Explanation - Purity reduces defects, decreasing electron scattering and resistivity.
Correct answer is: Lower electron scattering
Q.124 Which property of a conductor determines the magnitude of the skin effect at a given frequency?
Resistivity
Conductivity
Magnetic permeability
All of the above
Explanation - Skin depth depends on resistivity, conductivity, and magnetic permeability.
Correct answer is: All of the above
Q.125 Which of the following metals is most commonly used in high‑temperature wiring in furnaces?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.126 Which of the following is a major disadvantage of using copper in high‑frequency applications?
High cost
High skin effect
Low thermal conductivity
High density
Explanation - Copper’s finite skin depth increases losses at high frequencies.
Correct answer is: High skin effect
Q.127 Which of the following conductors is used for its low resistivity and high thermal stability in high‑power LEDs?
Copper
Aluminium
Nickel
Silver
Explanation - Silver’s low resistivity and good thermal conductivity make it suitable for high‑power LED heat spreading.
Correct answer is: Silver
Q.128 Which of the following properties is NOT affected by the addition of impurities to a metal conductor?
Electrical resistivity
Thermal conductivity
Melting point
Band structure
Explanation - Impurities mainly affect resistivity and thermal properties, not the fundamental band structure.
Correct answer is: Band structure
Q.129 Which of the following metals is used in high‑temperature superconducting (HTS) tapes?
Copper
Aluminium
YBCO (Yttrium Barium Copper Oxide)
Lead
Explanation - YBCO is a high‑temperature superconductor used in HTS tapes.
Correct answer is: YBCO (Yttrium Barium Copper Oxide)
Q.130 Which of the following conductors is commonly used in high‑frequency patch antennas?
Copper
Aluminium
Silver
Nickel
Explanation - Silver’s low resistivity reduces loss in high‑frequency antennas.
Correct answer is: Silver
Q.131 Which of the following factors has the largest impact on the resistivity of a metal at room temperature?
Temperature
Impurity level
Magnetic field strength
Pressure
Explanation - Impurities scatter electrons, significantly affecting resistivity.
Correct answer is: Impurity level
Q.132 Which of the following is a key property of a conductor used in high‑temperature electric furnaces?
High resistivity
High melting point
High electron mobility
High magnetic permeability
Explanation - High melting point ensures the conductor does not melt at furnace temperatures.
Correct answer is: High melting point
Q.133 Which of the following materials is known for its excellent electrical conductivity and high density?
Silver
Gold
Copper
Aluminium
Explanation - Gold has good conductivity and a high density, making it ideal for precision electronics.
Correct answer is: Gold
Q.134 Which of the following is the main cause of the increase in resistance of a copper wire when it is heated to 200 °C?
Oxidation
Electron–phonon scattering
Magnetic field induction
Chemical reaction with air
Explanation - Higher temperature increases lattice vibrations, causing more electron scattering and higher resistance.
Correct answer is: Electron–phonon scattering
Q.135 Which of the following metals is commonly used for high‑temperature wiring in furnaces?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.136 Which property of a conductor determines the magnitude of the skin effect at a given frequency?
Resistivity
Conductivity
Magnetic permeability
All of the above
Explanation - Skin depth depends on resistivity, conductivity, and magnetic permeability.
Correct answer is: All of the above
Q.137 Which of the following metals is used as a conductor in high‑frequency PCBs due to its low dielectric loss?
Copper
Aluminium
Silver
Gold
Explanation - Silver has minimal dielectric loss, preserving signal integrity at high frequencies.
Correct answer is: Silver
Q.138 Which of the following properties is NOT affected by the addition of impurities to a metal conductor?
Electrical resistivity
Thermal conductivity
Melting point
Band structure
Explanation - Impurities mainly affect resistivity and thermal properties, not the fundamental band structure.
Correct answer is: Band structure
Q.139 Which of the following is a direct consequence of using a higher purity metal in a conductor?
Higher resistivity
Lower conductivity
Lower electron scattering
Higher melting point
Explanation - Purity reduces defects, decreasing electron scattering and resistivity.
Correct answer is: Lower electron scattering
Q.140 Which metal is commonly used as a conductor for high‑temperature electric heaters?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.141 Which of the following is NOT a typical characteristic of a good conductor?
Low resistivity
High electron mobility
High band gap
High thermal conductivity
Explanation - Good conductors have small or zero band gaps; a high band gap indicates an insulator.
Correct answer is: High band gap
Q.142 Which of the following conductors is most suitable for cryogenic applications?
Copper
Aluminium
Silver
High‑temperature superconductor
Explanation - Superconductors have zero resistance at cryogenic temperatures.
Correct answer is: High‑temperature superconductor
Q.143 Which of the following metals is NOT used as a conductor in power distribution?
Copper
Aluminium
Lead
Silver
Explanation - Lead’s high resistivity makes it unsuitable for power distribution.
Correct answer is: Lead
Q.144 Which of the following is a direct consequence of the skin effect on AC current?
Lower effective resistance
Higher effective resistance
No change in resistance
Reduced current density near the surface
Explanation - AC current flows near the surface, reducing effective cross‑sectional area and increasing resistance.
Correct answer is: Higher effective resistance
Q.145 Which metal is most corrosion‑resistant among common conductors?
Silver
Gold
Copper
Aluminium
Explanation - Gold does not oxidize, giving it the highest corrosion resistance.
Correct answer is: Gold
Q.146 Which of the following properties does NOT affect the resistivity of a metal conductor?
Temperature
Purity
Magnetic field
Current density
Explanation - Resistivity is intrinsic and depends on temperature, purity, and magnetic field, not on current density.
Correct answer is: Current density
Q.147 Which property of a conductor determines the maximum current it can carry before overheating?
Resistivity
Cross‑sectional area
Conductivity
Melting point
Explanation - A larger area reduces resistance and heat generation, allowing higher currents.
Correct answer is: Cross‑sectional area
Q.148 Which of the following metals is commonly used as a conductor in high‑frequency PCBs due to its low dielectric loss?
Copper
Aluminium
Silver
Gold
Explanation - Silver has minimal dielectric loss, preserving signal integrity at high frequencies.
Correct answer is: Silver
Q.149 Which of the following is a major disadvantage of using copper in high‑frequency applications?
High cost
High skin effect
Low thermal conductivity
High density
Explanation - Copper’s finite skin depth increases losses at high frequencies.
Correct answer is: High skin effect
Q.150 Which of the following metals is used in high‑temperature wiring in furnaces?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.151 Which of the following is a key property of a conductor used in high‑temperature electric heaters?
High resistivity
High melting point
High electron mobility
High magnetic permeability
Explanation - High melting point ensures the conductor does not melt at furnace temperatures.
Correct answer is: High melting point
Q.152 Which of the following metals is known for its excellent electrical conductivity and high density?
Silver
Gold
Copper
Aluminium
Explanation - Gold has good conductivity and a high density, making it ideal for precision electronics.
Correct answer is: Gold
Q.153 Which of the following metals is used in high‑temperature electric heaters?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.154 Which of the following properties is NOT affected by the addition of impurities to a metal conductor?
Electrical resistivity
Thermal conductivity
Melting point
Band structure
Explanation - Impurities mainly affect resistivity and thermal properties, not the fundamental band structure.
Correct answer is: Band structure
Q.155 Which of the following is a direct consequence of using a higher purity metal in a conductor?
Higher resistivity
Lower conductivity
Lower electron scattering
Higher melting point
Explanation - Purity reduces defects, decreasing electron scattering and resistivity.
Correct answer is: Lower electron scattering
Q.156 Which metal is commonly used as a conductor for high‑temperature electric heaters?
Copper
Aluminium
Nickel
Silver
Explanation - Nickel can withstand high temperatures while maintaining conductivity.
Correct answer is: Nickel
Q.157 Which of the following is NOT a typical characteristic of a good conductor?
Low resistivity
High electron mobility
High band gap
High thermal conductivity
Explanation - Good conductors have small or zero band gaps; a high band gap indicates an insulator.
Correct answer is: High band gap
Q.158 Which of the following conductors is most suitable for cryogenic applications?
Copper
Aluminium
Silver
High‑temperature superconductor
Explanation - Superconductors have zero resistance at cryogenic temperatures.
Correct answer is: High‑temperature superconductor
Q.159 Which of the following metals is NOT used as a conductor in power distribution?
Copper
Aluminium
Lead
Silver
Explanation - Lead’s high resistivity makes it unsuitable for power distribution.
Correct answer is: Lead
Q.160 Which of the following is a direct consequence of the skin effect on AC current?
Lower effective resistance
Higher effective resistance
No change in resistance
Reduced current density near the surface
Explanation - AC current flows near the surface, reducing effective cross‑sectional area and increasing resistance.
Correct answer is: Higher effective resistance
Q.161 Which metal is most corrosion‑resistant among common conductors?
Silver
Gold
Copper
Aluminium
Explanation - Gold does not oxidize, giving it the highest corrosion resistance.
Correct answer is: Gold
Q.162 Which of the following properties does NOT affect the resistivity of a metal conductor?
Temperature
Purity
Magnetic field
Current density
Explanation - Resistivity is intrinsic and depends on temperature, purity, and magnetic field, not on current density.
Correct answer is: Current density