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# Multiple choice question for engineering

## Set 1

1. Which of the following is correct equation for De Broglie’s wavelength λ?
a) λ=h /mv
b) λ=h /m
c) λ=h /v
d) λ=mv/ h

Answer: a [Reason:] De Broglie’s wavelength λ=h⁄mv. λ represents wavelength, h is Plancks constant, m represent mass and v represents velocity.

2. With increase in mean free path of a crystal, conductivity of a crystal.
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned

Answer: a [Reason:] Conductivity increases with increase in mean free path of crystal. Conductivity is inversely proportional to resistance of material.

3. Resistivity of silver in ohm-m has an order of :
a) 10-2
b) 10-3
c) 10-5
d) 10-9

Answer: d [Reason:] Silver has lowest conductivity so resistivity is equal to 10-9 ohm-m.

4. Resistivity of iron in ohm-m has an order of :
a) 10-2
b) 10-6
c) 10-5
d) 10-9

Answer: b [Reason:] Iron has medium conductivity so resistivity is equal to 10-6 ohm-m. Silver has lowest conductivity.

5. Resistivity of bismuth in ohm-m has an order of :
a) 10-4
b) 10-3
c) 10-5
d) 10-9

Answer: a [Reason:] Bismuth has low conductivity so resistivity is equal to 10-4. Silver has lowest conductivity.

6. For insulators value of Energy gap in electron Volt i.e. eV ranges as :
a) Eg < 3
b) Eg < 1
c) Eg > 1
d) Eg > 3

Answer: d [Reason:] For insulator Electric gap is very large and is generally greater than 3eV. It requires large energy to cross electron along the gap.

7. Which of the following equation may represent the property of metal, if Eg stands for energy gap in electron volt?
a) Eg < 3
b) Eg < 1
c) Eg > 1
d) Eg > 3

Answer: b [Reason:] For conductors Electric gap is very small and is generally smaller than 1eV. For insulator Electric gap is very large and is generally greater than 3eV.

8. Resistance of a 200 meter long cooper wire is equal to 20 ohm. Its diameter is 0.44mm. Its specific resistance in ohm-m is equal to :
a) 1.520 * 10-8
b) 1.520 * 10-7
c) 1.520 * 10-6
d) 1.520 * 10-5

Answer: a [Reason:] A = 3.14*d2/4 and resistivity = R*A/l, where ‘a’ is the area of cross section of wire and ρ is specific resistance.

9. Resistance of a 10 meter long cooper wire is equal to 2 ohm. Its diameter is 0.44mm. Its specific resistance in ohm-m is equal to :
a) 1.520 * 10-8
b) 3.041* 10-8
c) 1.520 * 10-6
d) 1.520 * 10-5

Answer: b [Reason:] A = 3.14*d2/4 and resistivity = R*A/l, where ‘a’ is the area of cross section of wire and ρ is specific resistance.

10. With increase in temperature of a semiconductor, resistance of semiconductor.
a) Increases
b) Decreases
c) Remains Constant
d) None of the mentioned

Answer: b [Reason:] Semiconductor have negative temperature coefficient of resistance. There resistance increases with decrease in temprature.

## Set 2

1. Which of the following is un-conventional machining process?
a) Grinding
b) Milling
c) Turning
d) Electro chemical machining

Answer: d [Reason:] Electro chemical machining is an un-conventional machining process used for large material removal from the surface using electricity generated due to chemical reactions.

2. Which of the following is conventional machining process?
a) Electro chemical machining
b) Milling
c) Electron discharge machining
d) None of the mentioned

Answer: b [Reason:] Milling is a conventional machining process used for material removal from the surface.

3. In ECM, heavy electrical sparks are created.
a) True
b) False

Answer: b [Reason:] Sparks are generated in EDM, by using high voltage current, for proper erosion of material.

4. In ECM, tool does not touch the work piece.
a) True
b) False

Answer: a [Reason:] Tool is very near to work piece but does not touch it in ECM.

5. Which of the following is correct about ECM?
a) Erosion of metal takes place as reverse process of electroplating
b) Thermal stresses are induced
c) Mechanical stresses are induced
d) None of the mentioned

Answer: a [Reason:] In ECM, erosion of metal takes place as reverse process of electroplating.

6. Which of the following material cannot be machined using electro chemical machining?
a) Iron
b) Aluminum
c) Copper
d) Wood

Answer: d [Reason:] Wood is a bad conductor of electricity and hence cannot be machined using electro chemical machining.

7. Which of the following material can be machined using electro chemical machining?
a) Iron
b) Rubber
c) Plastic
d) Wood

Answer: a [Reason:] Iron is a good conductor of electricity and hence can be machined using electro chemical machining.

8. Electrode gap in electro chemical machining is generally ranges from
a) 0.5 mm to 0.9 mm
b) 1.1 mm to 1.2 mm
c) 0.1 mm to 0.2 mm
d) 3.1 mm to 4.2 mm

Answer: c [Reason:] Electrode gap in electro chemical machining is generally ranges from 0.1 mm to 0.2 mm.

9. Electrolytes used in ECM must posses
a) Low electrical conductivity
b) Low chemical stability
c) High electrical conductivity
d) None of the mentioned

Answer: c [Reason:] Electrolytes used in ECM must have high electrical conductivity.

10. Which of the following is not a function of electrolyte in ECM?
a) It completes the circuit
b) It helps in electrochemical reaction
c) It carries away heat and waste product
d) It provide non reactive environment

Answer: d [Reason:] Electrolyte provide reactive environment for chemical reactions to takes place.

## Set 3

1. Methods of mechanical surface treatments are
a) shot peening
b) laser shot peening
c) water jet peening
d) all of the mentioned

Answer: d [Reason:] The various methods of mechanical surface treatments includes a) shot peening b) laser shot peening c) water jet peening d) ultrasonic peening e) roller burnishing f) explosive hardening

2. Mechanical plating is also called
b) peen plating
d) none of the mentioned

Answer: b [Reason:] In mechanical plating (also called mechanical coating, impact plating, or peen plating), fine metal particles are compacted over the workpiece surfaces by glass, ceramic, or porcelain beads that are propelled by rotary means (such as tumbling).

3. Thermal spraying includes coatings of
a) carbides
b) ceramics
c) polymers
d) all of the mentioned

Answer: d [Reason:] Thermal spraying is a series of processes in which coatings of various metals, alloys, carbides, ceramics, and polymers are applied to metal surfaces by a spray gun with a stream heated by an oxyfuel flame, an electric arc, or a plasma arc.

4. In ________________, oxyfuel flame melts the wire and deposits it on the surface.
a) thermal wire spraying
b) thermal metal powder spraying
c) detonation gun
d) none of the mentioned

Answer: a [Reason:] The oxyfuel flame melts the wire and deposits it on the surface. The bond is of medium strength, and the process is relatively inexpensive.

5. Conversion coating is also called
a) anodizing
b) chemical reaction priming
c) coloring
d) none of the mentioned

Answer: b [Reason:] Conversion coating, also called chemical-reaction priming, is the process of producing a coating that forms on metal surfaces as a result of chemical or electrochemical reactions. Various metals (particularly steel, aluminum, and zinc) can be conversion coated. Oxides that naturally form on their surfaces represent a form of conversion coating.

6. Classification of paints are
a) enamels
b) lacquers
c) water based paints
d) all of the mentioned

Answer: d [Reason:] Paints generally are classified as a) Enamels: Produce a smooth coat with a glossy or semi-glossy appearance. b) Lacquers: Form a film by evaporation of a solvent. c)Water-based paints: Applied easily, but have a porous surface and absorb water, making them more difficult to clean than the first two types.

7. The methods of metal cleaning are
a) mechanical cleaning
b) electrolytic cleaning
c) chemical cleaning
d) all of the mentioned

8. Processes of chemical cleaning are
a) solution
b) saponification
c) emulsification
d) all of the mentioned

Answer: d [Reason:] Chemical cleaning usually involves the removal of oil and grease from surfaces. The operation consists of one or more of the following processes: a) Solution: The soil dissolves in the cleaning solution. b) Saponification: A chemical reaction converts animal or vegetable oils into a soap that is soluble in water. c) Emulsification: The cleaning solution reacts with the soil or lubricant deposits and forms an emulsion; the soil and the emulsifier then become suspended in the emulsion. d) Dispersion: The concentration of soil on the surface is decreased by surface active elements in the cleaning solution. e) Aggregation: Lubricants are removed from the surface by various agents in the cleanser and are collected as large dirt particles.

9. Which of these are cleaning fluids?
a) alkaline solutions
b) emulsions
c) solvents
d) all of the mentioned

Answer: d [Reason:] Common cleaning fluids used in conjunction with electrochemical processes for more effective cleaning include the following: a) Alkaline solutions: A complex combination of water-soluble chemicals, alkaline solutions are the least expensive and most widely used cleaning fluids in manufacturing operations. Small parts may be cleaned in rotating drums or barrels. Most parts are cleaned on continuous conveyors by spraying them with the solution and rinsing them with water. b) Emulsions: Emulsions generally consist of kerosene and oil-in-water and various types of emulsifiers. c) Solvents: Typically petroleum solvents, chlorinated hydrocarbons, and mineral spirits, solvents generally are used for short runs. Fire and toxicity are major hazards. d) Hot vapors: Chlorinated solvents can be used to remove oil, grease, and wax. The solvent is boiled in a container and then condensed. This hot-vapor process is simple, and the cleaned parts are dry. e) Acids, salts, and mixtures of organic compounds: These are effective in cleaning parts covered with heavy paste or oily deposits and rust.

10. Type of laser surface treatments are
a) heating
b) melting
c) vaporization
d) all of the mentioned

Answer: d [Reason:] Type of laser surface treatments are a) heating b) melting c) vaporization d) peening

## Set 4

1. The _____________ process uses a polystyrene pattern.
a) investment casting
b) ceramic-shell casting
c) evaporative-pattern casting
d) none of the mentioned

Answer: c [Reason:] The evaporative-pattern casting process uses a polystyrene pattern, which evaporates upon contact with molten metal to form a cavity for the casting. This process is also known as lost-foam casting and falls under the trade name full-mold process.

2. The _______________ process is used to make typical parts such as gears, cams, valves etc.
a) investment casting
b) ceramic-shell casting
c) evaporative-pattern casting
d) none of the mentioned

Answer: a [Reason:] The investment-casting process, also called the lost-wax process, was first used during the period from 4000 to 3000 B.C. Typical parts made are components for office equipment, as well as mechanical components such as gears, cams, valves, and ratchets.

3. In __________________ two halves of a mold are made from materials with high resistance.
a) investment casting
b) permanent-mold casting
c) evaporative-pattern casting
d) none of the mentioned

Answer: b [Reason:] In permanent-mold casting (also called hard-mold casting), two halves of a mold are made from materials with high resistance to erosion and thermal fatigue, such as cast iron, steel, bronze, graphite, or refractory metal alloys.

4. To increase the life of permanent molds, the surfaces of the mold cavity usually are coated with a
a) refractory slurry
b) silver
b) aluminum
d) none of the mentioned

Answer: a [Reason:] In order to increase the life of permanent molds, the surfaces of the mold cavity usually are coated with a refractory slurry (such as sodium silicate and clay) or sprayed with graphite every few castings. These coatings also serve as parting agents and as thermal barriers, thus controlling the rate of cooling of the casting.

5. __________ is an alternative to investment, shell-mold, and green-sand casting.
a) Vacuum Casting
b) Permanent-mold casting
c) Evaporative-pattern casting
d) None of the mentioned

Answer: a [Reason:] Vacuum casting is an alternative to investment, shell-mold, and green-sand casting and is suitable particularly for thin-walled (0.75 mm) complex shapes with uniform properties.

6. Hollow castings with thin walls can be made by permanent-mold casting using
a) vacuum casting
b) slush casting
c) evaporative-pattern casting
d) none of the mentioned

Answer: b [Reason:] Hollow castings with thin walls can be made by permanent-mold casting using this principle: a process called slush casting. This process is suitable for small production runs and generally is used for making ornamental and decorative objects (such as lamp bases and stems) and toys from low-melting-point metals such as zinc, tin, and lead alloys.

7. In ______________ the molten metal is forced upward by gas pressure into a graphite or metal mold.
a) vacuum casting
b) slush casting
c) pressure casting
d) none of the mentioned

Answer: c [Reason:] In pressure casting (also called pressure pouring or lou/-pressure casting), the molten metal is forced upward by gas pressure into a graphite or metal mold.

8. _____________ are made of two or more different materials.
a) Composite molds
b) Centrifuging
c) Die casting
d) none of the mentioned

Answer: a [Reason:] Composite molds are made of two or more different materials and are used in shell molding and other casting processes. They generally are employed in casting complex shapes, such as impellers for turbines.

9. In ____________ the metal is heated to just above its solidus temperature and poured into a vessel to cool it down to the semisolid state.
a) vacuum casting
b) rheocasting
c) pressure casting
d) none of the mentioned

Answer: b [Reason:] In rheocasting, the metal is heated to just above its solidus temperature and poured into a vessel to cool it down to the semisolid state. The slurry is then mixed and delivered to the mold or die.

10. The advantages of semisolid metal forming over die casting are
a) the structures developed are homogeneous, with uniform properties
b) casting as well as wrought alloys can be used
c) the lower superheat results in shorter cycle times
d) all of the mentioned

Answer: d [Reason:] The advantages of semisolid metal forming over die casting are a) the structures developed are homogeneous, with uniform properties, lower porosity, and high strength b) both thin and thick parts can be made c) casting as well as wrought alloys can be used d) parts subsequently can be heat treated, e) the lower superheat results in shorter cycle times. However, material and overall costs are higher than those for die casting.

## Set 5

1. Applications of sand casting include
a) machine bases
b) large turbine impellers
c) propellers
d) all of the mentioned

Answer: d [Reason:] Typical applications of sand casting include machine bases, large turbine impellers, propellers, plumbing fixtures, and a wide variety of other products and components.

2. Sand casting consists of
a) placing a pattern in sand to make an imprint
b) incorporating a gating system
c) removing the pattern and filling the mold cavity with molten metal
d) all of the mentioned

Answer: d [Reason:] Basically, sand casting consists of a) placing a pattern (having the shape of the desired casting) in sand to make an imprint, b) incorporating a gating system, c) removing the pattern and filling the mold cavity with molten metal, d) allowing the metal to cool until it solidifies, e) breaking away the sand mold, and f) removing the casting

3. _________ are used to mold the sand mixture into the shape of the casting and may be made of wood, plastic, or metal.
a) Vents
b) Patterns
c) Cores
d) None of the mentioned

Answer: b [Reason:] Patterns are used to mold the sand mixture into the shape of the casting and may be made of wood, plastic, or metal. The selection of a pattern material depends on the size and shape of the casting, the dimensional accuracy and the quantity of castings required, and the molding process.

4. _________ fill the flask uniformly with sand under a high-pressure stream.
a) Sandslingers
b) Patterns
c) Cores
d) None of the mentioned

Answer: a [Reason:] Sandslingers fill the flask uniformly with sand under a high-pressure stream, they are used to fill large flasks and are operated typically by machine.

5. In _________, the sand is compacted by a controlled explosion or instantaneous release of compressed gases.
a) vacuum molding
b) impact molding
c) all of the mentioned
d) none of the mentioned

Answer: b [Reason:] In impact molding, the sand is compacted by a controlled explosion or instantaneous release of compressed gases whine in vacuum molding the pattern is covered tightly with a thin sheet of plastic.

6. In __________ the pattern is covered tightly with a thin sheet of plastic.
a) vacuum molding
b) impact molding
c) all of the mentioned
d) none of the mentioned

Answer: a [Reason:] In vacuum molding (also known as the V process), the pattern is covered tightly with a thin sheet of plastic while in impact molding, the sand is compacted by a controlled explosion or instantaneous release of compressed gases.

7. Shell-molding applications include
a) small mechanical parts requiring high precision
b) such as gear housings
d) all of the mentioned

Answer: d [Reason:] Shell-molding applications include small mechanical parts requiring high precision, such as gear housings, cylinder heads, and connecting rods. The process also is used widely in producing high-precision molding cores.

8. In the plaster-molding process, the mold is made of plaster of paris with the addition of tale and __________ flour.
a) copper
b) iron
c) silica
d) none of the mentioned

Answer: c [Reason:] In the plaster-molding process, the mold is made of plaster of paris (gypsum or calcium sulfate) with the addition of tale and silica flour to improve strength and to control the time required for the plaster to set.

9. Typical parts such as impellers, cutters for machining operations are made by
a) plaster-molding process
b) ceramic-mold casting process
c) shell -molding
d) none of the mentioned