All Free Electrical Engineering MCQs with Answers
Every Electrical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
3,143 questions · page 154 of 158
- A. 15 to 20 per cent
- B. 35 to 45 per cent
- C. 70 to 80 per cent
- D. 90 to 95 per ceut
Explanation: A practical steam power plant loses efficiency through boiler, turbine, generator, condenser and pumping losses, so its overall Rankine…
Correct answer: 35 to 45 per cent- A. 700 W/m2
- B. 800 W/m2
- C. 1 kW/m2
- D. 2 kW/m2
Explanation: Solar irradiance at the Earth's surface on a clear sunny day is commonly approximated as 1 kW/m², although it varies with location, time…
Correct answer: 1 kW/m2- A. using focusing collector or heliostates
- B. using flat plate collectors
- C. using a solar pond
- D. any of the above system
Explanation: Solar thermal power can use concentrating collectors or heliostats, low-temperature flat-plate systems, and solar ponds to produce heat…
Correct answer: any of the above system- A. mechanical
- B. chemical
- C. heat
- D. sound
Explanation: A fuel cell produces electricity through an electrochemical reaction, directly converting the chemical energy of a fuel and oxidant into…
Correct answer: chemical- A. human waste
- B. wet cow dung
- C. wet livestock waste
- D. all above
Explanation: Biogas is formed by anaerobic decomposition of organic wastes, including human waste, wet cow dung, and other livestock waste.
Correct answer: all above- A. high CO content in flue gases at exit
- B. high CO2 content in flue gases at exit
- C. high temperature of flue gases
- D. the smoking exhaust from chimney
Explanation: Incomplete combustion leaves unburnt carbon compounds and produces excess carbon monoxide, so a high CO concentration in the flue gas is…
Correct answer: high CO content in flue gases at exit- A. 21%
- B. 23%
- C. 77%
- D. 79%
Explanation: Dry atmospheric air contains approximately 21% oxygen by volume, with most of the remainder being nitrogen.
Correct answer: 21%- A. 18%
- B. 23%
- C. 77%
- D. 79%
Explanation: Oxygen makes up about 23% of atmospheric air by mass because oxygen is heavier than nitrogen. By volume, its proportion is about 21%.
Correct answer: 23%- A. solar, wind and biomass
- B. fossil fuels, hydropower and nuclear energy
- C. wood, animal wastes and agriculture wastes
- D. none of the above
Explanation: Commercial energy sources are traded or supplied through organized energy systems, such as fossil fuels, hydropower, and nuclear energy.
Correct answer: fossil fuels, hydropower and nuclear energy- A. primary transmission
- B. secondary transmission
- C. primary distribution
- D. secondary distribution
Explanation: A three-phase four-wire arrangement provides three phase conductors plus a neutral, allowing both three-phase loads and single-phase…
Correct answer: secondary distribution- A. dry weather
- B. winter
- C. summer heat
- D. humid weather
- E. none of the above
Explanation: Moist air contains ions and lowers the dielectric strength of the surrounding air, making ionisation and corona more likely.
Correct answer: humid weather- A. Quartz
- B. Kaolin
- C. Felspar
- D. Silica
Explanation: Porcelain insulators are commonly made from kaolin, feldspar and quartz.
Correct answer: Silica- A. Steel cored aluminium
- B. Galvanised steel
- C. Cadmium copper
- D. Any of the above
Explanation: Steel-cored aluminium, galvanised steel and cadmium copper have all been used as overhead-line conductors for different strength and…
Correct answer: Any of the above- A. corona losses are minimum
- B. reactance is high
- C. sending end voltage is more
- D. receiving end voltage is more
Explanation: For a given system and sending conditions, reducing corona loss leaves more of the generated power available for transmission.
Correct answer: corona losses are minimum- A. distributors
- B. generating stations
- C. service mains
- D. all of the above
Explanation: A feeder carries bulk power from a substation or generating source to distribution points, called distributors.
Correct answer: distributors- A. reduces power factor
- B. corrodes the material
- C. gives odour
- D. transfer energy to the ground
- E. none of the above
Explanation: Corona produces ozone, and ozone is a strong oxidising agent that attacks and corrodes metal and insulation materials.
Correct answer: corrodes the material- A. 400 V
- B. 11 kV
- C. 66 kV
- D. 400 kV
Explanation: Large industrial consumers are commonly supplied at 11 kV to reduce current and distribution losses while avoiding the very high voltage…
Correct answer: 11 kV3078. The spacing between phase conductors of a 220 kV line is approximately equal to________________?
- A. 2 m
- B. 3.5 m
- C. 6 m
- D. 8.5 m
Explanation: A 220 kV overhead line requires wider phase spacing to withstand its higher electric stress and limit flashover risk.
Correct answer: 6 m- A. 4.3 m
- B. 5.5 m
- C. 7.0 m
- D. 10.5 m
Explanation: Higher-voltage lines need greater ground clearance for safety and to prevent flashover during normal operation or voltage surges.
Correct answer: 7.0 m- A. lead
- B. rubber
- C. copper
- D. iron
Explanation: Lead is commonly used as an underground-cable sheath because it is impervious to moisture and provides good chemical and corrosion…
Correct answer: lead