Multiple choice question for engineering
Set 1
1. For casting operation, a metal must be heated to what temperature?
a) Above solidifying temperature
b) Above vapourising temperature
c) Above melting temperature
d) Above room temperature
Answer
Answer: c [Reason:] For casting operations to take place, the metal to be casted must be heated above the melting temperature. The casting cannot be done at room temperature, as the metal needs to be liquefied first.
2. Which of the following is not a furnace used for heating?
a) Cupola furnace
b) Crucible furnace
c) Electric arc furnace
d) Blow air furnace
Answer
Answer: d [Reason:] Among the following, blow air furnace is not a type of furnace which is used for the heating purposes, whereas cupola, crucible and electric arc, are furnaces which are regularly used for heating.
3. Heat required to raise the temperature to the melting point is called what?
a) Sensible heat
b) Latent heat
c) Calorific heat
d) Specific heat
Answer
Answer: a [Reason:] Heat required to raise the temperature to the melting point is called as sensible heat. When there is a change of state of a material, keeping temperature constant, that heat is called as latent heat.
4. The heat needed for change of state of a material without changing the temperature is called what?
a) Sensible heat
b) Latent heat
c) Calorific heat
d) Specific heat
Answer
Answer: b [Reason:] The heat needed for change of state of a material without changing the temperature is called as latent heat. Latent heat is also referred to as hidden heat.
5. If there is an increase in the mass of the metal being heated, how would it affect the total heat energy required to raise the temperature of metal?
a) Increases
b) Decreases
c) No affect
d) Quantities not related
Answer
Answer: a [Reason:] With an increase in the mass of the metal which is being heated, there would be an increase in the total heat energy which is required to raise the temperature of the metal.
6. What is the unit of specific heat of solid metal?
a) J/kg
b) J °C/kg
c) J/kg °C
d) °C/kg
Answer
Answer: c [Reason:] The units to measure the specific heat of a solid metal or that of a liquid metal is given by J °C/kg, where Joule is unit of energy, Celcius is the unit of temperature and kg is the unit of mass.
7. When the molten metal is put into the mold, what is that temperature called?
a) Melting temperature
b) Vapourising temperature
c) Pouring temperature
d) Room temperature
Answer
Answer: c [Reason:] For a molten metal to be able to be poured, the temperature which it is required to possess is called as pouring temperature. This temperature is higher than the melting temperature, but lower than melting temperature.
8. In any flow through a system, if the area of cross section in which the metal is flowing, decreases, how will it affect the velocity?
a) Increases
b) Decreases
c) No affect
d) Quantities not related
Answer
Answer: a [Reason:] If the area of cross section of the system through which the molten metal is flowing, gets decrease, then the velocity of the flow would increase, as the two hold an inverse relation.
9. What is the shape of the sprue?
a) Cuboidal
b) Cubicle
c) Trapezoidal
d) Spherical
Answer
Answer: c [Reason:] The sprue is essentially tapered, giving it a trapezoidal look. It needs to be tapered, because of the inverse relation between area and velocity.
10. According to Bernoulli’s theorem, energies at two points in a flowing liquid are equal.
a) True
b) False
Answer
Answer: a [Reason:] According to Bernoulli’s theorem, the energies at two points in a flowing liquid, in a system having equal or unequal cross section areas, at same or different heights, are equal.
Set 2
1. The oil of which metal is used in high frequency induction furnace?
a) Zinc
b) Copper
c) Aluminium
d) Iron
Answer
Answer: b [Reason:] In a high frequency induction furnace, the refractory is placed inside the water cooled copper oil and is packed into its position by ramming it.
2. A high frequency induction furnace can melt metal up to what mass?
a) 10 tons
b) 11 tons
c) 12 tons
d) 13 tons
Answer
Answer: c [Reason:] A high frequency induction furnace is used for melting of comparatively small quantities. Metals up to the mass of 12 tons can be melted using this process.
3. What causes uniformity in the melt composition?
a) Electric stirring
b) Electric shaking
c) Magnetic stirring
d) Magnetic shaking
Answer
Answer: c [Reason:] For ensuring uniformity, a magnetic stirrer is employed, in a high frequency induction furnace. This magnetic stirrer distributes the composition of the melt excellently as needed.
4. Which currents are used for inducing heat in the high frequency induction furnace?
a) Alternating primary currents
b) Direct primary currents
c) Alternating secondary currents
d) Direct secondary currents
Answer
Answer: c [Reason:] A heavy amount of alternating secondary current, by electromagnetic induction, is induced in the metal charge. This causes the metal to get heated, because of the resistance offered by the metal charge.
5. How much is the thermal efficiency of a coreless high frequency induction furnace?
a) 50%
b) 60%
c) 70%
d) 80%
Answer
Answer: b [Reason:] As compared to a core type furnace, a coreless high frequency induction furnace has a lower efficiency. The thermal efficiency of a coreless furnace can be only up to 60%.
6. What is the minimum frequency accepted for the motor, used in current production of high frequency induction furnace?
a) 430 cycles/second
b) 500 cycles/second
c) 550 cycles/second
d) 600 cycles/second
Answer
Answer: b [Reason:] In high frequency induction furnace, motors which are equipped for the production of high frequency current can have a minimum frequency of 500 cycles every second.
7. In high frequency induction furnace, time taken by charge to melt is long.
a) True
b) False
Answer
Answer: b [Reason:] The process of melting is done very quickly by conduction and radiation, and magnetic stirring makes uniform distribution of the melt composition, which reduces time. Hence time taken by the charge to melt is short.
8. What is the minimum frequency accepted for the spark gap converter, used in current production of high frequency induction furnace?
a) 10,000 cycles/second
b) 15,000 cycles/second
c) 20,000 cycles/second
d) 25,000 cycles/second
Answer
Answer: c [Reason:] Spark gap converters which are equipped for the production of high frequency current can have a minimum frequency of 20,000 cycles every second, in high frequency induction furnace.
9. What is the maximum frequency accepted for the motor, used in current production of high frequency induction furnace?
a) 5000 cycles/second
b) 10000 cycles/second
c) 7500 cycles/second
d) 12500 cycles/second
Answer
Answer: b [Reason:] Motors which are equipped for the production of high frequency current can have a maximum frequency of 10000 cycles every second, in high frequency induction furnace.
10. What is the maximum frequency accepted for the spark gap converter, used in current production of high frequency induction furnace?
a) 70,000 cycles/second
b) 75,000 cycles/second
c) 80,000 cycles/second
d) 85,000 cycles/second
Answer
Answer: c
Set 3
1. How is the die used in injection molding cooled?
a) Oil
b) Air
c) Water
d) Contact with cold surface
Answer
Answer: c [Reason:] When it comes to molding of polymers in thermoplastics, injection molding process is the most common of the methods. In this method, whenever the die has to be cooled, there is water used to cool it.
2. How does the piston in the clamping unit move?
a) Hydraulic energy
b) Pneumatic energy
c) Heat energy
d) Suction
Answer
Answer: a [Reason:] There is a clamping unit employed for holding the two halves together and for the opening and closing of the mold. A moving piston is provided which operates the power press. This piston works on hydraulic energy.
3. Where does the granular molding material get loaded into?
a) Barrel
b) Hopper
c) Pellets
d) Split
Answer
Answer: b [Reason:] In a ram or plunger type injection molding system, the granular molding material has to be first loaded into a hopper, after which, with the help of a feeding device it gets metered out inside a cylinder.
4. Which of the following material is not made by injection molding?
a) Nuts
b) Tubes
c) Car handles
d) Electrical fittings
Answer
Answer: b [Reason:] Injection molding is one of the most widely used method of molding among molding with polymers. There are various applications of this method such as, nuts, bolts, cups, car handles, electrical fitting parts, but not tubes and rods.
5. What is the minimum temperature allowed to be given to the injection molding process?
a) 120°C
b) 130°C
c) 140°C
d) 150°C
Answer
Answer: d [Reason:] In the molding process of polymers in thermoplastics, injection molding process is the most common of the methods. The minimum allowable temperature that can be given to the system is 150°C.
6. Which of the following factors is not considered in a ram type injection molding?
a) Inner pressure of material
b) Outer pressure of material
c) Volume of material
d) Temperature of material
Answer
Answer: c [Reason:] Among the following, the inner pressure of the material, the outer pressure of the material as well as the mold and the temperature of the material and mold are important factors to be considered. The volume of material is not counted among important factors.
7. What is the minimum pressure allowed to be given to the injection molding process?
a) 90 MPa
b) 100 MPa
c) 140 MPa
d) 170 MPa
Answer
Answer: b
8. What is the maximum temperature allowed to be given to the injection molding process?
a) 300°C
b) 320°C
c) 350°C
d) 400°C
Answer
Answer: a [Reason:] The maximum allowable temperature that can be given to the system is 300°C, in this particular method of molding.
9. The barrel is used for opening and closing of the mold.
a) True
b) False
Answer
Answer: b [Reason:] A barrel is an instrument which is placed near the nozzle, and it plays no role in the opening and closing of the mold. There is a clamping unit employed for holding the two halves together and for the opening and closing of the mold.
10. There is a varied pressure provided in the solidification unit of injection molding process.
a) True
b) False
Answer
Answer: b [Reason:] Injection molding is considered to be one of the most widely used method. In this method, there are dies which eject the solidified component, before which it is kept under constant pressure.
Set 4
1. Which of the following defects are not detected by magnetic particle inspection?
a) Surface cracks
b) Quenching cracks
c) Thermal cracks
d) Fatigue cracks
Answer
Answer: a [Reason:] Quenching cracks, thermal cracks, grinding cracks or fatigue cracks are a few types of defects which can be detected by magnetic particle test, whereas surface cracks are defects which can be detected by simple visual inspection.
2. When an AC current is used for magnaflux test, what is its frequency?
a) 35 cycles/sec
b) 45 cycles/sec
c) 55 cycles/sec
d) 65 cycles/sec
Answer
Answer: c [Reason:] A magnaflux test is the one which is used for testing and detecting for any kind of thermal defect or any kind of quenching crack. For doing this, an alternating current can be used. The frequency of the alternating current is in the range of 50 to 60 cycles every second.
3. Which of the following materials can be tested using magnetic particle testing?
a) Brass
b) Steel
c) Bronze
d) Solder
Answer
Answer: b [Reason:] Among the following materials, only ferrous materials can be tested using magnetic particle test, which is therefore steel. Brass and bronze are copper alloys and solder is an alloy of zinc, lead and tin.
4. Which current is helpful in detecting sub surface discontinuities?
a) High frequency AC
b) Low frequency AC
c) Full wave DC
d) Half wave DC
Answer
Answer: c
5. Which current is helpful in detecting surface breaking indication?
a) High frequency AC
b) Low frequency AC
c) Full wave DC
d) Half wave DC
Answer
Answer: d
6. Magnetic particles with fluorescent coating are seen under which light?
a) White light
b) Infrared light
c) Black light
d) Ultraviolet light
Answer
Answer: d [Reason:] In magnetic particle testing, only ferrous materials can be tested using magnetic particle test. The casting which is undergoing magnetic inspection, if it is coated with fluorescence, then it has to be viewed in an ultraviolet light only.
7. What is the skin depth of copper at 60 Hz frequency?
a) 8 mm
b) 8.5 mm
c) 9 mm
d) 9.5 mm
Answer
Answer: b [Reason:] The distribution of an alternating electric current inside the conductor, and the flow of current through the skin of the material is called skin effect. The depth of the skin effect is skin depth. For copper, at frequency 60 Hz, the skin depth is 8.5mm.
8. What is the size range of dry particle powder?
a) 5 to 170 micrometers
b) 15 to 185 micrometers
c) 45 to 215 micrometers
d) 65 to 250 micrometers
Answer
Answer: a [Reason:] Dry particle powder is basically applied in the form of a spray or a cloud. This powder is designed to be seen in white light. The particle size of dry particle powder is 5 to 170 micrometers.
9. Half wave DC is more penetrative in magnaflux testing than full wave DC.
a) True
b) False
Answer
Answer: a [Reason:] For the detection of sub surface defects, a full wave direct current is needed. For the detection of surface breaking indication, a half wave direct current is needed. A half wave direct current is more penetrative than full wave direct current.
10. Magnetic field lines travel from north to south.
a) True
b) False
Answer
Answer: a [Reason:] Magnetic field lines are imaginary lines, which travel from north pole of the magnet to the south pole of the magnet. These lines do not travel through the specimen, but around it.
Set 5
1. Pure magnesium melts at what temperature?
a) 600°C
b) 650°C
c) 700°C
d) 750°C
Answer
Answer: b [Reason:] The temperature at which the pure form of magnesium gets ignited by itself is 473°C, and the temperature at which magnesium in its purest form is found to melt is 650°C.
2. Which of the following metals is least used in making magnesium alloys?
a) Aluminium
b) Zinc
c) Copper
d) Manganese
Answer
Answer: c [Reason:] Magnesium metal in itself is not one of the strongest metals and is hence adulterated with other materials to form strong alloys. Among the following, aluminium, zinc and manganese are highly used in making magnesium alloys.
3. Which of the following can be the casting temperature for magnesium alloys?
a) 630°C
b) 760°C
c) 850°C
d) 970°C
Answer
Answer: b [Reason:] When it comes to casting of magnesium alloys, the casting temperatures have to be kept in real control, that is, if the temperatures go too high, the metal might catch fire. The temperature range for casting magnesium alloys is 720°C to 800°C.
4. Which of the following is not a property of a magnesium alloy?
a) High damping capacity
b) High electrical conductivity
c) Good fatigue strength
d) High thermal resistivity
Answer
Answer: d [Reason:] Magnesium on getting mixed with other elements starts possessing many different properties. It contains good damping capacity, good electrical conductivity and good fatigue strength, but not, thermal resistivity.
5. What is the color of pure magnesium metal?
a) Red
b) White
c) Black
d) Yellow
Answer
Answer: b [Reason:] The purest form of magnesium is considered to be in its weakest form, and hence other elements are added in it to enhance its quality. The physical qualities too change on addition of other elements. Originally, the color of pure magnesium metal is silvery white.
6. What should be the temperature of the mixture while alloying takes place?
a) 550°C
b) 600°C
c) 650°C
d) 700°C
Answer
Answer: d [Reason:] During the mixture getting processed, first the magnesium is melted, and then zinc metal is added. Aluminum is mixed in it through stirring. While this is happening, it has to be ensured, that the complete alloying process takes place at 700°C.
7. In magnesium alloys, what is the maximum amount of allowed aluminum?
a) 11%
b) 13%
c) 19%
d) 24%
Answer
Answer: a [Reason:] Magnesium alloys are basically a composition of various metals mixed with magnesium to improve its physical, chemical, mechanical and thermal properties. In this, the maximum allowable aluminum that can be added is only 11%.
8. What should the temperature ideally be to remove the casting after making of magnesium alloys?
a) Below 450°C
b) Below 300°C
c) Below 350°C
d) Below 300°C
Answer
Answer: d [Reason:] It is always advisable that, the castings should never be removed too quickly, as it might lead to distortion of the cast, because it is still hot. Therefore, when the temperature of the cast is below 300°C, the magnesium alloy cast can be removed.
9. In grain refinement process, only hexachlorobenzene is used.
a) True
b) False
Answer
Answer: b [Reason:] In grain refinement process, there is another process called carbon inoculation, in which, tablets of organic compounds are used, namely hexachlorobenzene and hexachloroethane.
10. Magnesium alloys have a low strength to weight ratio.
a) True
b) False
Answer
Answer: b [Reason:] Magnesium alloys possess many desirable mechanical, physical and thermal properties, which may help in better casting processes. One of these property is a high strength to weight ratio.
11. In sand casting of magnesium alloys, what is the amount of silica sand used in an American mix?
a) 80 lb
b) 90 lb
c) 100 lb
d) 110 lb
Answer
Answer: c [Reason:] It is mainly observed that, magnesium alloys are manufactured with the help of sand molds only. The amount of silica sand used in magnesium alloys is 100 lbs in both British mix and American mix.
12. In sand casting of magnesium alloys, what is the amount of bentonite sand used in a British mix?
a) 3 lb
b) 4 lb
c) 5 lb
d) 6 lb
Answer
Answer: b [Reason:] In the production of magnesium alloys, there are variety of sands employed. For this, bentonite sand has to be used for the sand casting of the alloys. The amount of bentonite sand used is 4 lbs in both British as well as American mix.