Carbon nanotubes and graphene applications – MCQs – EE

1. Carbon nanotubes (CNTs) are cylindrical structures made up of:
(A) Carbon atoms arranged in hexagonal lattices
(B) Silicon atoms arranged in cubic lattices
(C) Iron and oxygen compounds
(D) Aluminum oxide crystals

2. Graphene is a:
(A) Single layer of carbon atoms arranged in a honeycomb lattice
(B) Multiple layers of silicon
(C) Polymer composite material
(D) Metallic thin film

3. Single-walled carbon nanotubes (SWCNTs) consist of:
(A) One graphene sheet rolled into a tube
(B) Multiple graphene layers
(C) Metal nanowires
(D) Carbon spheres

4. Multi-walled carbon nanotubes (MWCNTs) are composed of:
(A) Multiple concentric graphene cylinders
(B) Silicon nanowires
(C) Carbon nanoparticles only
(D) Polymer shells

5. The electrical conductivity of graphene is primarily due to:
(A) Free movement of π-electrons
(B) High resistivity
(C) Ionic conduction
(D) Magnetic behavior

6. CNTs can exhibit:
(A) Metallic or semiconducting properties depending on chirality
(B) Only metallic behavior
(C) Only semiconducting behavior
(D) Insulating properties

7. The chiral angle of a carbon nanotube determines its:
(A) Electrical properties (metallic or semiconducting)
(B) Color
(C) Density
(D) Thermal conductivity only

8. Graphene has an exceptional carrier mobility of approximately:
(A) 200,000 cm²/V·s
(B) 100 cm²/V·s
(C) 10,000 cm²/V·s
(D) 500 cm²/V·s

9. The mechanical strength of graphene is approximately:
(A) 200 times stronger than steel
(B) Equal to copper
(C) Half as strong as iron
(D) Weaker than aluminum

10. CNTs have a typical diameter range of:
(A) 0.4–50 nm
(B) 100–500 nm
(C) 1–10 µm
(D) 1–10 mm

11. Graphene-based transistors are promising alternatives to silicon because of:
(A) High electron mobility and low power consumption
(B) Low conductivity
(C) High switching delay
(D) Large bandgap

12. CNTs are widely used in field emission displays (FEDs) because they:
(A) Have low work function and high aspect ratio
(B) Emit light directly
(C) Reflect electrons
(D) Absorb X-rays

13. In supercapacitors, graphene and CNTs are used as:
(A) High surface area electrode materials
(B) Electrolyte solutions
(C) Insulating layers
(D) Separator films

14. Graphene oxide (GO) is primarily used for:
(A) Energy storage and flexible electronics
(B) Magnetic sensors
(C) Optical fibers
(D) Permanent magnets

15. CNTs improve the mechanical and electrical properties of materials when used as:
(A) Reinforcement in composites
(B) Lubricants
(C) Coolants
(D) Solvents

16. The main method for large-scale synthesis of CNTs is:
(A) Chemical Vapor Deposition (CVD)
(B) Electrolysis
(C) Photolithography
(D) Arc welding

17. Graphene sheets can be produced by:
(A) Mechanical exfoliation
(B) Electrolysis of water
(C) Heat treatment of copper
(D) Mixing polymers

18. CNTs are used in nanoelectronics as:
(A) Transistor channels and interconnects
(B) Power transformers
(C) Insulators
(D) Light bulbs

19. Graphene can replace indium tin oxide (ITO) in:
(A) Transparent conductive electrodes
(B) Magnetic cores
(C) Heat sinks
(D) Ceramic substrates

20. CNTs are used in sensors due to their:
(A) High sensitivity to molecular adsorption
(B) Low reactivity
(C) High mass density
(D) Large size

21. The thermal conductivity of graphene is around:
(A) 5000 W/m·K
(B) 50 W/m·K
(C) 100 W/m·K
(D) 500 W/m·K

22. CNTs in energy storage devices enhance:
(A) Charge capacity and current density
(B) Resistance
(C) Weight
(D) Voltage drop

23. Graphene-based materials are ideal for flexible electronics because they are:
(A) Strong, thin, and highly conductive
(B) Rigid and brittle
(C) Insulating and opaque
(D) Magnetic and dense

24. CNTs are often used as interconnects in integrated circuits because of their:
(A) High electrical conductivity and mechanical strength
(B) Magnetic properties
(C) Low melting point
(D) High thermal expansion

25. Graphene is a zero-bandgap material, making it suitable for:
(A) High-speed analog devices
(B) Optical amplifiers
(C) Magnetic storage
(D) Insulators

26. CNTs exhibit ballistic transport of electrons, meaning:
(A) Electrons move with minimal scattering
(B) Electrons are trapped
(C) Electrons reflect continuously
(D) Electrons lose energy rapidly

27. Graphene nanoribbons (GNRs) can have a tunable bandgap depending on:
(A) Width and edge structure
(B) Temperature
(C) Pressure
(D) Magnetic field only

28. The main environmental concern with CNTs and graphene is:
(A) Toxicity and environmental persistence
(B) Rapid degradation
(C) Lack of conductivity
(D) High melting point

29. CNTs are used in antistatic coatings because they:
(A) Conduct electricity and prevent charge accumulation
(B) Block magnetic fields
(C) Reflect light
(D) Absorb heat

30. The future applications of CNTs and graphene in electrical engineering include:
(A) Flexible displays, nano transistors, and high-capacity energy storage
(B) Mechanical gears
(C) Hydraulic systems
(D) Optical lenses only