Multiple choice question for engineering
1. What is the attribute of a material which resists the flow of electricity known?
c) Dielectric strength
Answer: d [Reason:] Resistivity is that attribute of a material which resists the flow of electricity, while conductivity is its reciprocal (or) opposite. The process by which two dissimilar metals join and produce a voltage is known as thermoelectricity. The dielectric strength of a material is its insulating capacity against voltage.
2. How is conductivity of a material defined?
Answer: c [Reason:] Electrical conductivity is defined by
, whereas its reciprocal defines the electrical resistivity given by
or the ratio of magnitudes of an electrical field to the electrical density
. Permeability is a magnetic property which is defined by
3. What is the electrical conductivity of Aluminum?
a) 6.3 * 107
b) 5.9 * 107
c) 3.5 * 107
d) 1 * 107
Answer: c [Reason:] The electrical conductivity of Aluminum is 3.5 * 107. The electrical conductivity of Silver, Copper, and Iron is 6.3 * 107, 5.9 * 107, and 1 * 107 in that order. The electrical conductivity is generally measured at 20oC.
4. What is the electrical resistivity of Copper?
a) 1.59 * 10-8
b) 1.68 * 10-8
c) 2.65 * 10-8
d) 5.9 * 10-8
Answer: b [Reason:] The electrical resistivity of Copper is 1.68 * 10-8. The electrical resistivity of Silver, Aluminum, and Zinc is 1.59 * 10-8, 2.65 * 10-8, and 5.9 * 10-8 in that order. The electrical resistivity is generally measured at 20oC.
5. Measured using an Electrical Conductivity meter, what is the order of resistivity of superconducting materials?
Answer: d [Reason:] The resistivity of superconducting materials is 0 since they conduct all electricity and resist none of it. Metals have the resistivity of the order of 10-8 while that of insulators is of the order of 1016. Since maximum electricity is refused by super-insulators, their resistivity is .
6. Which of the following represents the energy band diagram of a semiconducting material?
Answer: b [Reason:] The diagram with the short energy gap represents the energy band diagram of semiconductor, which in this case is silicon. The diagram with multiple valence bands denotes that of a conductor, which in this case is sodium. The diagram with a wide energy gap represents an insulator like a diamond. The diagram having no energy gap is not an energy band diagram.
7. Which of the following processes is not an application of thermoelectric effect?
a) Seebeck effect
b) Peltier effect
c) Thomson effect
d) Ettingshausen effect
Answer: d [Reason:] Seebeck, Peltier, and Thomson are three distinct effects which make up the thermoelectric effect. Ettingshausen effect, however, is a separate thermoelectric phenomenon like the Nernst effect.
8. The insulating capacity of a material against high voltages is known as _______
a) Dielectric strength
c) Electromechanical effect
d) Electrochemical effect
Answer: a [Reason:] The dielectric strength of a material is its insulating capacity against a high voltage. The process by which two dissimilar metals join and produce a voltage is known as thermoelectricity. The electrical effect in a material is the relation between electrical energy and chemical change (as in batteries) and that of electromechanical effect is in an electrically operated mechanical device (as radar).
9. What is the nature of the coefficient of resistance of an insulator?
Answer: d [Reason:] The coefficient of resistance of an insulator and a semiconductor material is generally negative. It is usually positive for pure metals. Zero coefficient values can be obtained by alloying with a specific type of metals.
10. What is the dielectric strength of mica?
a) 118 MV/m
b) 2000 MV/m
c) 3 MV/m
d) 1012 MV/m
Answer: a [Reason:] The dielectric strength of mica is 118 MV/m. It is generally measured at 20oC, where 1 MV/m equals 10 V/m. The dielectric strengths of diamond, air, and vacuum are 2000, and 10 in MV/m in that order.
1. The ability of a material to return to its original state when an external force is removed is called __________
Answer: b [Reason:] When force is applied, materials undergo deformation. The ability of a material to resist this deformation by regaining its original state upon removal of the force is called elasticity. Plasticity is considered as the converse of elasticity.
2. The stress-strain curve can be expressed linearly by the use of _________
a) Cauchy’s principle
b) Fourier series
c) Taylor’s series
d) D’Alembert theorem
Answer: c [Reason:] The stress-strain curve is used to describe the elasticity of materials. This curve is generally non-linear. However, Taylor’s series may be used to express it linearly for small deformations.
3. For an isentropic material, the stress-strain relationship is known as _________
a) Bragg’s law
b) Hooke’s law
c) Lenz law
d) Sokolov-Ternov effect
Answer: b [Reason:] The stress-strain curve is used to describe the elasticity of materials which is generally non-linear. For an isentropic material, the linearized stress-strain relationship is called Hooke’s law.
4. Viscoelasticity exhibits which of the following properties?
c) Temperature and time dependent
d) Temperature and time independent
Answer: c [Reason:] Viscoelasticity differs from elasticity in that it does not completely return to its original state when the forces are removed. The viscoelastic behavior of the material is dependent on both time and temperature.
5. Which method is used for measuring the viscoelastic behavior of materials?
a) Resonant sphere technique
b) Rectangular parallelepiped resonance
c) Resonant sound resonance
d) Resonant ultrasound spectroscopy
Answer: d [Reason:] Broadband viscoelastic spectroscopy and resonant ultrasound spectroscopy are the two most widely preferred techniques for viscoelastic testing. These methods are preferred over the others due to their ability to be used above and below ambient temperatures and are more explicit for viscoelasticity.
6. Relaxation modulus is defined as __________
Answer: a [Reason:] Relaxation modulus is a time-dependent elastic modulus for viscoelastic materials and is denoted by Er(t). From the equation, σ(t) is the time dependant stress, whereas ∈o is the strain.
7. The elastic component of viscoelastic material is modeled as _________
Answer: a [Reason:] Viscoelastic materials are those which possess the characteristics of both viscosity and elasticity. The elastic components are modeled as springs, whereas the viscous components are modeled as dashpots.
8. A series connection between a Hookean spring and a Newtonian dashpot results is ________ model.
c) Standard linear solid model
d) Prony series
Answer: a [Reason:] Viscoelastic materials can be modeled as springs and dashpots to understand their behavior. A connection in series of a Hookean spring and a Newtonian dashpot gives the Maxwell model, whereas parallel connection gives the Kelvin-Voigt model.
9. The stress-strain relationship for viscous components is given by ________
Answer: c [Reason:] The viscous components of viscoelastic materials are modeled as dashpots. Their stress-strain relationship is expressed by σ= η dε/dt. The elastic components that are modeled as springs are expressed by the equation σ= E∈.
1. PMMA is otherwise known as _______
c) Polyvinyl fluoride
d) Perfluoroalkoxy ethylene
Answer: b [Reason:] Polymethyl methacrylate (PMMA) is a commonly used acrylic material. It is also commonly known as Perspex or Plexiglas. They are hard, easily formed, and readily colored polymers. PMMA is produced by the process of addition polymerization.
2. What does the numbered suffix used in nylon polymers mean?
a) Molecular weight
b) Number of carbon atoms
c) Coefficient of thermal expansion
d) Number of monomer chains
Answer: b [Reason:] Nylons, also known as polyamides, are polymers produced by a condensation reaction between an amine and an organic acid. The suffix indicates the number of carbon atoms, i.e. six carbon atoms in Nylon 6. A slash in the suffix denotes a copolymer, i.e. Nylon 6/12 is a copolymer of nylon 6 and nylon 12. Nylons are strong and abrasive resistant thermoplastics with good mechanical properties.
3. Acetals retain their properties up to ______
Answer: b [Reason:] An acetal is a product of polymerization of formaldehyde. They have a low coefficient of friction, good strength, and can retain its properties up to 120oC. They are also known as polyacetal and polyoxymethylene.
4. Which of the following is an example of heterochain polymers?
Answer: b [Reason:] Heterochain polymers are those which contain elements other than carbon in their molecular chain. A few examples of heterochain polymers are acetal, polycarbonate, and polyethylene terephthalate. Polycarbonates have good ductility, dimensional stability, and are transparent.
5. Polyethylene and polystyrene are examples of which kind of polymers?
a) Hydrocarbon plastics
b) Chlorocarbon polymers
c) Acrylic material
Answer: a [Reason:] Hydrocarbon plastics are a kind of thermoplastic polymers made by polymerization of hydrocarbons. The common hydrocarbon plastics are polyethylene(PE), polypropylene (PP), and polystyrene (PS).
6. Which of the following are applications of polypropylene?
a) Buckets, bottle crates
b) CD cases, food boxes
c) Wire insulation, piping
d) Valves, fittings
Answer: a [Reason:] Polypropylene is a high strength thermoplastic polymer which also has better stiffness than polyethylene. They are used for making buckets, battery cases, bottle and bottle caps etc. CD cases and food boxes are common applications of polystyrene. Wire insulation and piping are done using polyethylene.
7. Versalon, Zytel, and Plaskon are common trade names of which thermoplastic?
Answer: c [Reason:] Polyamides are strong and abrasive resistant plastics which are used as fasteners, bushings, and electrical parts. Their common trade names are Nylon, Versalon, Ultramid, Zytel, and Plaskon. Acetal’s trade names are Delrin and Celcon, while that of polycarbonate are Lexan and Merlon.
8. Thermal resistance of polyimide is ______
Answer: b [Reason:] Polyimide is a thermoplastic polymer which has good mechanical properties and a low coefficient of friction. It possesses excellent thermal resistance up to 250oC. They are used as bearings, seals, printed circuit boards, and fibers.
1. What is the unit of diffusion coefficient?
a) mol m-2 s-1
b) mol m-3
c) m2 s-1
d) KJ mol-1
Answer: c [Reason:] The unit of the diffusion coefficient (D) is mole per square meter per second (m2 s-1). The units of flux (J), concentration (c), and enthalpy ( are mol m2 s-1, mol m-3, and KJ mol-1 in that order.
2. What is Fick’s first law of diffusion?
Answer: a [Reason:] Equation
defines Fick’s first law of diffusion. It is used to describe flow under steady-state conditions. The equation
is the diffusion flux, which is a form of Fick’s first law.
3. Which of these represents concentration-distance profile for steady-state flow?
Answer: b [Reason:] The profile with a straight line represents steady-state flow, whereas the curved profile indicates unsteady state flow. Initial constant concentration indicates the carburization process of steel, while constant concentration towards the end shows decarburization process of steel.
4. What is Fick’s second law of diffusion?
Answer: a [Reason:] The equation
defines Fick’s second law of diffusion. It indicates flow under unsteady state condition. The outstanding choices are variations of the first law.
5. What is the diffusion constant (Do) when copper is dissolved in copper?
a) 0.2 * 10-4
b) 0.15 * 10-4
c) 1.98 * 10-4
d) 5400 * 10-4
Answer: a [Reason:] Diffusion of Cu in Cu has a Do value of 0.2 * 10-4 m2 s-1. The diffusion constants of Zn in Zn, Al in Al, and Si in Si are 0.15 * 10-4, 1.98 * 10-4, and 5400 * 10-4 in that order.
6. Plain carbon steels are alloys mainly consisting of _________
a) Iron and Carbon
b) Potassium and Iron
c) Carbon and Potassium
d) Carbon and Indium
Answer: a [Reason:] Steels are alloys having primary components as Iron and Carbon. They, however, contain elements such as silicon, manganese, phosphorous, and sulfur in varying quantities. These elements are added either intentionally, or retained during the refining process.
7. Which of the following attributes explain why pure metals are not frequently used in engineering applications?
Answer: c [Reason:] Pure metals are soft and ductile, which is not ideal for most engineering applications. Therefore, alloys are used to fulfill requirements. This explains why pure gold is mixed with impurities to make ornaments.
8. Which of the following is also known as mild steel?
a) Plain carbon steel
b) Low carbon steel
c) Medium carbon steel
d) High carbon steel
Answer: b [Reason:] Low carbon steels are otherwise known as mild steel owing to their carbon content. These are the carbon steels which contain less 0.30% of carbon. They are used for making small parts like wires, sheets, valves, and more.
9. What is the composition of carbon in medium carbon steels?
b) 0.1% – 0.3%
c) 0.25% – 0.6%
d) More than 0.6%
Answer: c [Reason:] Medium carbon steels are those steels which contain 0.25% – 0.6% of carbon, along with traces of manganese, silicon, and copper. Dead mild contains 0.05% of carbon, whereas another mild steel contains 0.1% – 0.3% of carbon. More than 0.6% of carbon is present in high-carbon steel.
10. Which of these are applications of high-carbon steel?
a) Gears, valves
b) Steel wires, sheets, screws
c) Clutch discs, valve springs
d) Machine tools, leaf and coil springs
Answer: d [Reason:] High-carbon steels with a tensile strength of 580 N/mm2 are used for making machine tools, leaf and coil springs, and similar tools. Medium-carbon steels (1230 N/mm2) are used for making clutch discs and valve springs. Mild steels (555 N/mm2) are used for making gears and valves, whereas dead mild steels (390 N/mm2) are used for making wires, sheets, and screws.
11. What is the maximum forging temperature of 1.1% carbon steel?
Answer: b [Reason:] Steels with 1.1% carbon composition are forged at 1082oC, while their burning temperature is 1171oC. Steels with 1.5% carbon, however, burn at 1140oC and are forged at 1049oC.
12. Which steels are generally used for making connecting rods and gear shafts?
a) Low carbon steels
b) Medium carbon steels
c) High carbon steels
d) Stainless steels
Answer: b [Reason:] Connecting rods and gear shafts are commonly made using medium carbon steels containing 0.35% to 0.45% carbon. They possess a tensile strength of 750 N/mm2. This gives the required strength and hardness to the parts.
13. What is the maximum amount of manganese in carbon steels?
Answer: a [Reason:] In plain carbon steels, the composition of steel must not exceed 1.65% of manganese. It is also restricted to a maximum of 0.60% for both copper and silicon, while carbon is limited to a maximum of 1.5%.
14. What are the advantages of plain carbon steels over alloy steels?
a) Inexpensive but hard to handle
b) Expensive but easy to handle
c) Inexpensive and easy to handle
d) There are no advantages of plain carbon steels
Answer: c [Reason:] Carbon steels are made of compositions having a limited quantity of elements. Due to factors such as common elements, limited quantities, and low strength, carbon steels are much cheaper than alloying steels.
1. Which nickel alloy is used as a substitute in tableware and jewelry?
Answer: d [Reason:] Nickel-silver is used as a low-cost substitute for silver in jewelry and tableware, by electroplating on the surface. Surprisingly, however, it does not contain any silver. They are added to appear silvery-white and improve corrosion resistance and strength. They can also be used for musical and scientific instruments, and marine applications.
2. Which of the following is an application of Inconel?
a) Furnace chamber
b) Chemical storage tank
d) Spray nozzles
Answer: a [Reason:] Inconel is a nickel-chromium alloy containing 80% nickel, 14% chromium, and 6% iron. They are used in chemical industries due to its excellent corrosion resistance. The leftover choices are examples of various Hastelloys.
3. What is the melting point of Tin?
Answer: d [Reason:] Tin is a non-toxic white, soft metal which has a low melting point of 231.9oC and a high boiling point of 2270oC. It becomes highly fluid when molten. This helps it as a coating for other metals.
4. Which of the following is a tarnish resistant alloy?
a) Soft solder
Answer: d [Reason:] Pewter is an alloy of tin containing 7% antimony and 2% copper. It is used as a tarnish resistant. It is easy to cast and worked into various shapes.
5. Soft solder is a _______ tin alloy.
Answer: a [Reason:] Soft solder is a tin alloy containing 20-70% tin and remaining lead. This eutectic structure, with 63% tin, is used in electrical industry. Alloys with 50% tin are a general purpose solder. Lower tin content (15-20%) is used for dipping solders for automotive radiator cores.
6. What effect does cobalt have on steel?
a) Increases hardenability
b) Decreases hardenability
c) Changes color
d) No change
Answer: b [Reason:] Cobalt reduces the hardenability of steel. When it is dissolved in ferrite, cobalt provides resistance to softening at high temperatures.
7. What is the melting point of titanium?
Answer: b [Reason:] Titanium is an element which is abundantly available on earth. At 885oC it transforms from alpha stage to beta stage. Its melting point is at 1680oC and boiling point is at 3287oC.
8. The alpha-beta titanium alloy is heat treatable up to _______
Answer: c [Reason:] Alpha-Beta alloys are the most widely used titanium alloys. This is because they are a combination of alpha and beta alloys. Alpha alloys are stable up to 540oC but are not heat-treatable. Beta alloys are heat-treatable up to 320oC. Alpha-Beta alloys are heat-treatable up to 430oC but are more difficult to weld.
9. Beryllium is a ductile material, before turning brittle at ______
Answer: d [Reason:] Beryllium is a brittle material which stops it from being easily fabricated and reduces performance. It becomes more ductile between 200-400oC. However, over 500oC, it becomes brittle again.