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Multiple choice question for engineering

Set 1

1. How many categories can the synchronous motors be divided into?
a) 4
b) 3
c) 5
d) 2

View Answer

Answer: c [Reason:] The synchronous motors can be divided into 5 types of categories. They are hydro-generators, turbo-alternators, engine driven generators, motors, compensators.

2. How is the hydro-generator driven by?
a) water turbine
b) steam turbine
c) internal combustion engines
d) control of reactive power networks

View Answer

Answer: a [Reason:] The synchronous generators which are driven by the water turbines are called as hydro-generators. The hydro-generators are also known as water wheel generators.

3. What is the rating of the hydro-generators?
a) 750 MW
b) 1000 MW
c) 20 MW
d) 700 MW

View Answer

Answer: a [Reason:] The synchronous generators which are driven by the water turbines are called as hydro-generators. The rating of the synchronous generators is 750 MW.

4. What is the speed by which the hydro-generators are driven?
a) 100-1000 rpm
b) 5000 rpm
c) 1500 rpm
d) 3000 rpm

View Answer

Answer: a [Reason:] The synchronous generators which are driven by the water turbines are called as hydro-generators. The hydro-generators are driven at a speed of 100-1000 rpm.

5. How is the turbo-alternators driven by?
a) water turbines
b) steam turbines
c) engine driven generators
d) compensators

View Answer

Answer: b [Reason:] The turbo alternators are one category among the synchronous machines. They are driven by the steam turbines.

6. What is the speed of the turbo-alternators?
a) 100-1000 rpm
b) 5000 rpm
c) 1500 rpm
d) 3000 rpm

View Answer

Answer: d [Reason:] The turbo alternators are one category among the synchronous machines. They are driven by the steam turbines. The rating of the turbo-alternators is 3000 rpm.

7. What is the rating of the turbo-alternators?
a) 750 MW
b) 1000 MW
c) 20 MW
d) 700 MW

View Answer

Answer: b [Reason:] The turbo alternators are one category among the synchronous machines. They are driven by the steam turbines. The speed of the turbo-alternators is 1000 MW.

8. How is the engine driven generators driven by?
a) water turbines
b) steam turbines
c) internal combustion engine
d) compensators

View Answer

Answer: c [Reason:] The engine driven generators are driven by the different forms of internal combustion engine. These generators have higher speeds for higher power ratings.

9. What is the rating of the engine driven generators?
a) 750 MW
b) 1000 MW
c) 20 MW
d) 700 MW

View Answer

Answer: c [Reason:] The engine driven generators are driven by the different forms of internal combustion engine. These generators have higher speeds for higher power ratings. These generators have ratings upto 20 MW.

10. What is the speed of the engine driven generators?
a) 100-1000 rpm
b) 5000 rpm
c) 1500 rpm
d) 3000 rpm

View Answer

Answer: c [Reason:] The engine driven generators are driven by the different forms of internal combustion engine. These generators have higher speeds for higher power ratings. These generators have speed of 1500 rpm.

11. The synchronous motors are cheaper than the induction motors?
a) true
b) false

View Answer

Answer: a [Reason:] The synchronous motors are cheaper than the induction motors. They have high power lower speed applications and are cheaper when compared to the induction motors.

12. Which among the following are the applications of synchronous motors?
a) compressors
b) blowers
c) fans
d) compressors, fans, blowers

View Answer

Answer: d [Reason:] They are mainly used in the high power and low speed applications. They include compressors, fans, blowers and low head pumps.

13. What is the application of synchronous compensators?
a) control of real power
b) control of active power
c) control of reactive power
d) control of apparent power

View Answer

Answer: c [Reason:] The main application of the synchronous compensators is to control the reactive powers. They are used in the power supply networks.

14. What is the rating of the synchronous generators?
a) 750 MVAr
b) 1000 MVAr
c) 100 MVAr
d) 700 MVAr

View Answer

Answer: c [Reason:] The main application of the synchronous compensators is to control the reactive powers. They are designed for ratings upto 100 MVAr.

15. What is the speed of the engine driven generators?
a) 100-1000 rpm
b) 5000 rpm
c) 1500 rpm
d) 3000 rpm

View Answer

Answer: d [Reason:] The main application of the synchronous compensators is to control the reactive powers. They are designed to speeds upto 3000 rpm.

Set 2

1. What is window space factor?
a) window space factor = copper area in the window – total window area
b) window space factor = copper area in the window + total window area
c) window space factor = copper area in the window * total window area
d) window space factor = copper area in the window / total window area

View Answer

Answer: d [Reason:] Window space factor is the ratio of the copper area in the window to the total window area. It is a constant used in the output equation of transformers.

2. What does the window space factor depends on?
a) it depends on the core
b) it depends on the armature
c) it depends on the insulation
d) it depends on the insulation and copper

View Answer

Answer: d [Reason:] Window space factor totally depends on the insulation of the machine. It also depends on the copper windings provided.

3. What does the insulation and copper of the transformer depends on?
a) current rating
b) voltage rating
c) output power
d) voltage rating and output power

View Answer

Answer: d [Reason:] The insulation and copper of the transformer depends on the voltage rating of the transformer. It also depends on the output power produced by the transformer.

4. What is the empirical formula for calculating the value of window space factor?
a) window space factor = 10 / (30+kV)
b) window space factor = 5 * (30+kV)
c) window space factor = 10 * (30+kV)
d) window space factor = 5 / (30+kV)

View Answer

Answer: a [Reason:] The output voltage in kV is calculated first. Then the value is substituted in the formula to obtain the empirical value of the window space factor.

5. What is the empirical value of window space factor, given the output is 1000kV?
a) 0.09
b) 0.9
c) 0.009
d) 0.0009

View Answer

Answer: c [Reason:] Empirical value of window space factor = 10 / (30+kV) kV = 1000 kV, empirical value = 10/1030 = 0.009.

6. What is the ratings of the transformers for using the empirical value of window space factor?
a) 50-100 kVA
b) 50-150 kVA
c) 50-200 kVA
d) 100-200 kVA

View Answer

Answer: c [Reason:] The empirical formula of the window space factor is used for the transformers of the rating 50-200 kVA. If the transformer rating is higher than 200 kVA then the empirical formula isn’t used.

7. What is the relationship of the space factor value with the large and small outputs?
a) small value for both large and small outputs
b) large values for both large and small outputs
c) large value for small output and small value for large outputs
d) small value for small output and large value for large outputs

View Answer

Answer: d [Reason:] The space factor is directly proportional to the output. If large output is obtained, space factor is high and vice versa.

8. What is the formula for the window space factor, when the output is 1000 kVA?
a) 12 / (30+kV)
b) 10 / (30+kV)
c) 9 / (30+kV)
d) 11 / (30+kV)

View Answer

Answer: a [Reason:] 10 / (30+kV) denotes the empirical value of window space factor for rating between 50-200 kilo-volt-amp. When the output is near 1000 kilo-volt-amp then the formula used is 12/(30+kV).

9. What is the formula of window space factor, when the transformer rating is 20 kVA?
a) 10 / (30+kV)
b) 12 / (30+kV)
c) 8 / (30+kV)
d) 19 / (30+kV)

View Answer

Answer: c [Reason:] 10 / (30+kV) denotes the empirical value of window space factor for rating between 50-200 kilo-volt-amp. 12 / (30+kV) is the window space factor for transformers having rating around 1000 kVA.

10. The area of the window depends on the window space factor?
a) true
b) false

View Answer

Answer: a [Reason:] Area of the window = Total conductor area / window space factor. The area of the window is indirectly proportional to the window space factor.

Set 3

1. What factor does the rotor body depends upon in the construction of hydro-generators?
a) speed
b) voltage
c) peripheral voltage
d) power

View Answer

Answer: c [Reason:] In the hydro-generators the salient poles are attached to the rotor body. The type of rotor body used depends in general on the peripheral speed.

2. Which machine makes use of the forged steel construction?
a) low speed
b) high speed
c) very high speed
d) medium speed

View Answer

Answer: b [Reason:] The forged steel construction is made use for the high speed machines. The earliest construction particularly at relatively low outputs consisted of a body and shaft extension made as single forging.

3. In what type of generator is the thick rolled steel discs made use of?
a) generators running at 400 rpm
b) generators running at 500 rpm
c) generators running at 600 rpm
d) generators running at 600 rpm and above

View Answer

Answer: d [Reason:] Another type of rotor construction made use of in the hydro-generators is the thick rolled steel discs. It is made use for the generators running at 600 rpm and above.

4. What is the range of the length of the thick rolled sheets used in the rotor design of the hydro generators?
a) 130-180 mm
b) 120-180 mm
c) 150-180 mm
d) 160-190 mm

View Answer

Answer: b [Reason:] The minimum value of the length of the thick rolled sheets used in the rotor design of the hydro-generators is 120 mm. The maximum value of the length of the thick rolled sheets used in the rotor design of the hydro-generators is 180 mm.

5. The laminations used in the rotor body design is 1.8 mm?
a) true
b) false

View Answer

Answer: a [Reason:] The laminations used in the rotor body design is 1.8 mm. They are in the form of the overlapping segments tightly bolted.

6. For what peripheral speed of the machine is the segmental rim on fabricated spider used?
a) >120 m per s
b) <120 m per s
c) >130 m per s
d) <130 m per s

View Answer

Answer: d [Reason:] The segmental rim on fabricated spider is used for the machines whose peripheral speed is upto 130 m per s. The advantage is it is easy to transport and assemble at site.

7. For what peripheral speed is the poles bolted to the yoke?
a) 20 m per s
b) 30 m per s
c) 25 m per s
d) 27 m per s

View Answer

Answer: c [Reason:] The poles are clamped or fixed to the rim in different ways. In case of the generators the poles are bolted to the yoke when the peripheral speed is upto 25 m per s.

8. What is the range of the peripheral speeds in the water wheel generators?
a) 20 to 80 m per s
b) 20 to 50 m per s
c) 50 to 80 m per s
d) 30 to 70 m per s

View Answer

Answer: a [Reason:] The minimum peripheral speed in the water wheel generators is 20 m per sec. The maximum peripheral speed in the water wheel generators is 80 m per sec.

9. The length of the mean turn of the winding is smallest with circular poles?
a) true
b) false

View Answer

Answer: a [Reason:] The circular poles have a lot of advantages. The length of the mean turn of the winding is smallest with circular poles and therefore cost is reduced. The copper losses are also less.

10. Why are damper windings used in the construction of hydro-generators?
a) to control losses
b) to increases efficiency
c) to reduce the oscillations
d) to reduces voltage surges

View Answer

Answer: c [Reason:] The damper windings are generally used in the construction of hydro-generators. It is generally used to reduce the oscillations in the generator.

11. By how much is the rotor and the turbine runner and the hydraulic thrust requirements more than the dead weight of rotating masses?
a) thrice
b) twice
c) by 4 times
d) by 8 times

View Answer

Answer: b [Reason:] In case of the vertical shaft generators special features have to be incorporated in the bearing set up. This is because the rotor and the turbine runner and the hydraulic thrust requirements is twice more than the dead weight of rotating masses.

12. How are the bearing cooled in the construction?
a) natural cooling
b) forced cooling
c) air cooling
d) oil cooling

View Answer

Answer: d [Reason:] Oil is the material which is used for the cooling of the bearings. It is being supplied to the bearings by the pump.

13. By how many minutes is the complete energy of the rotating parts and the machine is brought to rest?
a) 2 minutes
b) 1 minute
c) 3 minutes
d) 4 minutes

View Answer

Answer: c [Reason:] The brakes are so designed such that the complete energy of the rotating parts and the machine is brought to rest. It is brought to rest by 3 minutes.

14. What material is used to make the material of the pads of the brakes?
a) pads using asbestos
b) pads using metal wires
c) pads using copper
d) pads using the asbestos interlaced with metal wires.

View Answer

Answer: d [Reason:] The brakes are made to stop the machines immediately to protect the bearings. The brakes have pads using the asbestos interlaced with metal wires.

15. Why are the slip rings made use of?
a) they are used to provide excitation to field windings
b) they are used to provide excitation to the armature windings
c) they are used to reduce the heating effects
d) they are used to reduce the losses

View Answer

Answer: a [Reason:] The slip rings are the last construction material made use of in the hydro-generators construction. They are used to provide excitation to the field windings.

Set 4

1. The size_t integer type in C++ is?
a) Unsigned integer of at least 64 bits
b) Signed integer of at least 16 bits
c) Unsigned integer of at least 16 bits
d) Signed integer of at least 64 bits

View Answer

Answer: c [Reason:] The size_t type is used to represent the size of an object. Hence, it’s always unsigned. According to the language specification, it is at least 16 bits.

2. What is the output of the following program?

  1.     #include <iostream>
  2.     using namespace std;
  3.     int main()
  4.     {
  5.     	int x = -1;
  6.         unsigned int y = 2;
  7.  
  8.         if(x > y) 
  9.         {
  10.         	cout << "x is greater";
  11.     	}
  12.         else 
  13.         {
  14.     		cout << "y is greater";
  15.     	}      
  16.     }

a) x is greater
b) y is greater
c) implementation defined
d) arbitrary

View Answer

Answer: a [Reason:] x is promoted to unsigned int on comparison. On conversion x has all bits set, making it the bigger one.

3. Which of these expressions will return true if the input integer v is a power of two?
a) (v | (v + 1)) == 0;
b) (~v & (v – 1)) == 0;
c) (v | (v – 1)) == 0;
d) (v & (v – 1)) == 0;

View Answer

Answer: d [Reason:] Power of two integers have a single set bit followed by unset bits.

4. What is the value of the following 8-bit integer after all statements are executed?

  1. int x = 1;
  2. x = x << 7;
  3. x = x >> 7;

a) 1
b) -1
c) 127
d) Implementation defined

View Answer

Answer: d [Reason:] Right shift of signed integers is undefined, and has implementation-defined behaviour.

5. Which of these expressions will make the rightmost set bit zero in an input integer x?
a) x = x | (x-1)
b) x = x & (x-1)
c) x = x | (x+1)
d) x = x & (x+1)

View Answer

Answer: b

6. Which of these expressions will isolate the rightmost set bit?
a) x = x & (~x)
b) x = x ^ (~x)
c) x = x & (-x)
d) x = x ^ (-x)

View Answer

Answer: c

7. 0946, 786427373824, ‘x’ and 0X2f are _____ _____ ____ and _____ literals respectively.
a) decimal, character,octal, hexadecimal
b) octal, hexadecimal, character, decimal
c) hexadecimal, octal, decimal, character
d) octal, decimal, character, hexadecimal

View Answer

Answer: d [Reason:] Literal integer constants that begin with 0x or 0X are interpreted as hexadecimal and the ones that begin with 0 as octal. The character literal are written within ”.

8. What will be the output of this program?

  1.     #include <iostream>
  2.     using namespace std;
  3.     int main()
  4.     {
  5.         int a = 8;
  6.         cout << "ANDing integer 'a' with 'true' :" << a && true;
  7.         return 0;
  8.     }

a) ANDing integer ‘a’ with ‘true’ :8
b) ANDing integer ‘a’ with ‘true’ :0
c) ANDing integer ‘a’ with ‘true’ :1
d) None of the mentioned

View Answer

Answer: a

9. What will be output of this program?

  1.     #include <iostream>
  2.     using namespace std;
  3.     int main()
  4.     {
  5.         int i = 3;
  6.         int l = i / -2;
  7.         int k = i % -2;
  8.         cout << l << k;
  9.         return 0;
  10.     }

a) compile time error
b) -1 1
c) 1 -1
d) implementation defined

View Answer

Answer: b [Reason:] Sign of result of mod operation on negative numbers is sign of the dividend.

10. What will be output of this function?

  1.     int main()
  2.     {
  3.         register int i = 1;
  4.         int *ptr = &i;
  5.         cout << *ptr;
  6. 	return 0;
  7.     }

a) 0
b) 1
c) Compiler error may be possible
d) Runtime error may be possible

View Answer

Answer: c [Reason:] Using & on a register variable may be invalid, since the compiler may store the variable in a register, and finding the address of it is illegal.

Set 5

1. The installation time for a gas turbine power plant is ______________
a) Comparatively less than thermal power plant
b) Comparatively more than thermal power plant
c) Equal to thermal power plant
d) Very much longer than thermal power plant

View Answer

Answer: a [Reason:] Gas turbine power plant is comparatively simpler in construction than thermal power plant. So, its installation time is less than a thermal power plant for same capacity.

2. Which of the following is not used in gas turbine power plant?
a) Compressor
b) Turbine
c) Combustion chamber
d) Condenser

View Answer

Answer: d [Reason:] Natural gas itself or mixture of natural gas and air is used as working medium in gas turbine power plant. Condenser is a device or arrangement used to condense low pressure steam already used by turbine. There is no steam in gas turbine power plant so no condenser is required.

3. Which component of gas turbine power plant is main cause of its low efficiency?
a) Gas turbine
b) Combustion chamber
c) Compressor
d) Starting motor

View Answer

Answer: c [Reason:] The overall efficiency of gas turbine is low, because a greater part of power developed by the turbine ( about 65%) is used in driving the compressor.

4. What is intercooling in gas turbine power plant?
a) Removal of heat from combustion gas between stages of turbine
b) Removal of heat from compressor between stages of compressor
c) Removal of heat from intake air
d) Removal of heat from exhaust air

View Answer

Answer: b [Reason:] Intercooling means removal of heat from compressed air between low pressure and high pressure compressor. Cooling the low pressure compressed air reduces the air volume and improves the thermal efficiency, air rate and work ratio.

5. What is the function of regenerator?
a) Eatery compresses the exhaust gases
b) It heats the compressed air
c) It regenerates the combustible gas from exhaust gas
d) It regenerates the combustible oil from exhaust gas

View Answer

Answer: b [Reason:] Regenerator is usually of shell and tube construction. Regenerator uses the heat of exhaust gas to heat compressed air before it is sent to combustion chamber. This reduces the fuel consumption and improves the cycle thermal efficiency.

6. Fuel other than natural gas i.e. solid and liquid fuels can be used in _______
a) open cycle gas turbine power plant
b) closed cycle gas turbine power plant
c) open and closed cycle gas turbine power plant
d) only natural gas is used in gas turbine power plant

View Answer

Answer: b [Reason:] In closed cycle gas turbine power plant the working medium is heated externally and the fuel is not mixed with working fluid. This ensures the use of any fuel such as inferior type or solid type fuel.

7. Which of the following gas turbine power plant can use working medium of required property?
a) Closed cycle gas turbine power plant
b) Open cycle gas turbine power plant
c) Open and closed cycle gas turbine power plant
d) No gas turbine power plant can use working medium of required property.

View Answer

Answer: a [Reason:] A working medium with physical properties superior to those of air such as helium and hydrogen can be used in closed cycle gas turbine power plant. This is because of airtight construction of this plant.

8. What is the tariff in case of power system?
a) The taxes which a power plant pay to Indian government
b) The taxes which a power plant pay to state government
c) The taxes which a Power Grid pay to Indian government
d) The schedule of rates are charged of supply of electricity for consumers

View Answer

Answer: d [Reason:] Tariff means the schedule of rates are charges tariff. In case of electric supply means the schedule of rates framed for supply of electrical energy to different classes of consumer.

9. An electricity supplier is charging for the electricity as per the total load connected, fixed number of hours. This type of tariff will be a ___________
a) Simple tariff
b) Flat demand tariff
c) Flat rate tariff
d) Block rate tariff

View Answer

Answer: b [Reason:] When the use of Electricity was mainly restricted to very few applications such as for lamps it is ee and the number of hours of use of lamp were fixed they were charged on the basis of total load connected in Kilowatt and the fixed number of hours of use district is known as flat demand tariff.

10. Which statement about simple tariff is true?
a) Charges are made as per the total load connected and of fixed duration of use
b) Charges are made on the basis of units consumed in a certain period
c) Different types of consumers are charged differently
d) Charges per kilowatt decreases with increase in unit consumed

View Answer

Answer: b [Reason:] In simple tariff cost of energy is charged on the basis of unit consumed cost per KWh is given by summing annual fixed cost and annual operating cost and dividing it by total number of units applied to the consumer per annum.

11. Identify the type of tariff the consumer is charged Rs 4 per unit if the consumer does not exceed 50 KWh, Rs 3.50 per unit if the consumer does not exceed 50 KWh but less than 200 kilowatt hour, and Rs 3 per KWh if consumer exceeds 200 kilowatt hour.
a) Flat demand tariff
b) Simple tariff
c) Flat rate tariff
d) Step rate tariff

View Answer

Answer: d [Reason:] Step rate tariff is a group of flat rate tariff of decreasing unit charges for higher range of conception. Charges per KWh are reduced for increas in power consumption above different predefined step levels. This type of tariff takes into account the fact of lower generation cost going to higher energy consumption consequent to improvement of load factor.

12. What is demand factor of commercial consumers?
a) Low
b) Low
c) High
d) More than 1

View Answer

Answer: c [Reason:] Demand factor is the ratio of maximum demand to connected load. As we know maximum demand cannot be greater than connected load so demand factor is always less than one. Commercial consumer generally used as most of disconnected loads so their demand factor is high.

13. If an industrial consumer consumes 50KW for 4 hours, 300KW for 15 hours and 60KW for 5 hours daily and the tariff rate is Rs 5/KWh. What is the energy consumption in a month of 30 days?
a) Rs 750000
b) Rs 475000
c) Rs 755000
d) Rs 470000

View Answer

Answer: a [Reason:] Energy Consumed in one day = (50×4 + 300×15 + 60×5)KWh = 5000 KWh Energy Consumed in one month = 5000× 30 = 150000 KWh Hence, Charge on one month = 150000 × 5 =750000 Rupees.

14. Monthly consumption of a consumer is 500KWh. What will be the monthly bill at the following rate?
First 100 unit Rs 0.6/KWh
Next 100 units Rs 0.5/KWh
Remaining units Rs 0.4/KWh
a) Rs 250
b) Rs 25
c) Rs 230
d) Rs 23

View Answer

Answer: c [Reason:] 500 KWh = (100 +100 + 300) KWh Bill for one month consumption = (100×0.6 + 100×0.5 + 300×0.4) Rupees = 230 Rupees.