Category: Renewable Energy Objective Questions

Solar Energy Multiple Choice Questions on “Solar Collectors – 2”.

1. Which of the following is used to make a glass-glass evacuated tubes?
a) Borosilicate glass
b) Carbon
c) Wood
d) Plastic coating

Answer: a
Clarification: As the name suggests, glass-glass evacuated tubes is a type of evacuated-tube solar collector. It is made up of two borosilicate glass tubes fused together at one or both ends.

2. Which of the following is a problem with evacuated tubes?
a) Underheating
b) Overheating
c) Poor absorption of sunlight
d) Poor reception of sunlight

Answer: b
Clarification: Overheating is a common problem with evacuated-tube solar collector. This is because of the high temperatures of the circulating fluid caused by collection of large amount of sunlight.

3. Why does flat plate collector perceived to have higher efficiency than evacuated tube solar collector in terms of area?
a) Because flat plate collector has a large installation area
b) Because evacuated tube collector is compact
c) Because of the vacuum gap in evacuated tube collectors
d) Because of the vacuum gap in flat plate collectors

Answer: c
Clarification: In terms of area, flat plate solar collectors are generally perceived to have a higher efficiency than evacuated-tube solar collectors. This is because of the vacuum gap in evacuated tube collectors which increases their net occupied area.

4. _______ lose more heat to the environment than evacuated-tube solar collectors.
a) Photovoltaics
b) Solar stills
c) Solar air conditioners
d) Flat-plate collectors

Answer: d
Clarification: Flat-plate collectors lose more heat to the environment than evacuated-tube solar collectors. Photovoltaics, solar stills and solar air conditioners are not solar collectors.

5. Which of the following are combined to form an evacuated flat plate solar collector?
a) Flat plate solar collectors and evacuated-tube solar collectors
b) Flat plate solar collectors and bowl collectors
c) Bowl collectors and evacuated-tube solar collectors
d) Polymer collectors and bowl collectors

Answer: a
Clarification: Evacuated flat plate collectors combine the technologies of both, flat plate solar collectors and evacuated-tube solar collectors. There are not a combination of bowl and polymer type collectors.

6. Which of the following provides highest energy conversion efficiency in non-concentrating solar collectors?
a) Flat plate collectors
b) Evacuated flat plate collectors
c) Evacuated-tube collectors
d) Parabolic collectors

Answer: b
Clarification: Evacuated flat plate collectors provide the highest energy conversion efficiency in non-concentrating solar collectors. Parabolic collector is not a non-concentrating collector.

7. What is the metal sheet absorber surrounded with in an evacuated flat plate collector?
a) Low volume inside flat envelope
b) Low vacuum inside curved envelope
c) High vacuum inside flat envelope
d) Low vacuum inside thick curved envelope

Answer: c
Clarification: In an evacuated flat-plate solar collector, the metal sheet absorber is surrounded with a high vacuum. This is then placed inside a flat envelope made of glass and metal.

8. Which of the following organisations developed first high vacuum insulation?
a) NASA
b) IIT
c) Stanford
d) CERN

Answer: d
Clarification: CERN developed the first collector making use of high vacuum insulation. However, the first company to commercialise the technology was TVP SOLAR SA of Switzerland.

9. Why does an evacuated flat plate collector require a glass-metal seal?
a) To join the glass plate to the rest of metal envelope
b) To join the glass plate to a part of metal envelope
c) To disconnect the glass plate to the rest of plastic envelope
d) To disconnect the glass plate to the rest of metal envelope

Answer: a
Clarification: An evacuated flat plate collector requires a glass-metal seal. This is to join the glass plate to the rest of metal envelope. It also requires an internal structure to support such a plate against atmospheric pressure.

10. Which of the following pumps is used in an evacuated-tube solar collector?
a) Non-evaporable getter
b) Flash getter pump
c) Heat pump
d) Water pump

Answer: b
Clarification: Evacuated flat-plate solar collectors use a barium flash getter pump. This pump is used to keep the internal pressure stable throughout the operation. They do not use non-evaporable getter pumps.

11. Evacuated flat-plate solar collectors use _______ pumps.
a) Heat pump
b) Flash getter pump
c) Non-evaporable getter
d) Internal combustion

Answer: c
Clarification: Evacuated flat-plate solar collectors use non-evaporable getter (NEG) pumps to keep the internal pressure stable throughout the operation. This pump enables some regeneration in-situ by exposure to sunlight.

12. What advantage does polymer collector have over metal collector?
a) Better sales as they are produced in Europe
b) Poor sales as they are produced in Europe
c) They cannot be used in cold climate
d) They can be used in cold climate

Answer: d
Clarification: The primary advantage of a polymer collector over a metal collector is that they can be used in cold regions with low temperatures. This is because they are freeze-tolerant. Whether they are manufactured in Europe or not does is neither an advantage nor a disadvantage.

13. Bowl collectors operate similarly to _______
a) parabolic dish
b) flat plate collector
c) evacuated-tube collector
d) evacuated flat tube collector

Answer: a
Clarification: Bowl collectors operate similarly to a parabolic dish. However, they have a fixed receiver unlike a parabolic dish. This reduces efficiency but is much cheaper to build and operate.

14. Polymer flat plate collectors can use plain water.
a) True
b) False

Answer: a
Clarification: Polymer flat plate collectors can use plain water. This is because they are freeze-tolerant and do not require antifreeze agents to prevent water from solidifying.

15. Bowl collectors use a fixed curved receiver.
a) True
b) False

Answer: a
Clarification: Bowl collectors use a fixed curved receiver. They have a fixed spherical mirror with a tracking receiver.

Wind Energy Multiple Choice Questions on “Wind Turbine Siting”.

1. When looking for a wind site, assessors start by _______
a) determining the direction of prevailing wind at the site
b) looking for a good source of water
c) looking for a location with good sunlight
d) determining all the directions of the local wind

Answer: a
Clarification: To install a wind turbine, wind assessors look for locations with strong and smooth winds. They start by assessing the direction of the prevailing wind at the site. Generally, winds blowing in a particular direction are strong and smooth.

2. Which of the following is required for the installation of a wind turbine system?
a) A weak wind flow
b) A consistent and strong wind flow
c) Still air
d) A consistent wind flow with obstructions

Answer: b
Clarification: For a wind turbine system to run effectively, it requires a good wind site. A good wind site is one with a consistent and strong wind flow in a direction.

3. Which of the following is preferred in a good wind site?
a) Still air
b) A higher altitude terrain with objects obstructing the wind flow
c) A higher altitude terrain with no or minimum objects obstructing the wind flow
d) A lower altitude terrain with no or minimum objects obstructing the wind flow

Answer: c
Clarification: Terrain is known to affect wind speeds which in turn affect the efficiency of a wind turbine system. A higher altitude terrain with no or minimum objects obstructing the wind flow is always preferred.

4. What is the minimum height above which the rotor of the wind turbine system is installed in a good wind site?
a) 100 feet above the tallest obstacle within a 5-foot radius
b) 5 feet above the tallest obstacle within a 500-foot radius
c) 10 feet above the tallest obstacle within a 5000-foot radius
d) 30 feet above the tallest obstacle within a 500-foot radius

Answer: d
Clarification: A wind turbine can be located anywhere in a good wind site provided the rotor is installed slightly on a higher terrain. The rotor is typically mounted 30 feet above the tallest obstacle within a 500-foot radius.

5. Which of following are considered during wind siting?
a) Safety impact, community impact, environmental impact
b) Radiation
c) Sunlight
d) Water

Answer: a
Clarification: Before selecting and deciding on a good site, various impacts of installing a wind turbine are considered. The engineers ensure that the wind site does not harm any living creature. They also ensure that the site is far away from the nearest village to prevent any noise pollution.

6. Which of the following impacts a community/village/society due to installation of wind turbine system?
a) Private and Public cloud
b) Noise from the turbine, flicker
c) Private, Public and Hybrid cloud
d) Public and Hybrid cloud

Answer: b
Clarification: Noise, flicker and signal interference impacts the nearest community/society/village. The other options are not related to wind siting.

7. Does the wind turbine harm birds?
a) True
b) False

Answer: a
Clarification: The wind turbine system harms the birds and may even kill them. Thus, it is imperative to select a site with minimum or no living creatures.

8. Which of the following factors affect wind speed near the turbine system?
a) Birds flying
b) Sunlight
c) Time of the day, temperature, season
d) A village far away from the wind site

Answer: c
Clarification: Time of the day, temperature and season are a few factors affecting the wind speed. While the sun’s heat affects the wind speed by creating a pressure difference, sunlight in itself doesn’t. Affect of a far away village from the wind site and birds flying on wind speed is minimum.

9. Do wind sites need an access to transmission lines?
a) False
b) True

Answer: b
Clarification: Potential wind sites turning into wind farms need access to transmission lines. Transmission lines are used to transport the electrical energy generated from the wind turbine system to the grid.

10. Which of the following can make a good wind site?
a) A national sanctuary with wildlife
b) A city
c) A village
d) A barren land with wind speed of 6 on beaufort scale

Answer: d
Clarification: A barren land with a wind speed of 6 on beaufort scale is a potential wind site. A city, village or national sanctuary are poor choices for wind sites as they obstruct wind flow. Also, it is not safe to install a wind turbine in such places.

Biomass Energy Multiple Choice Questions on “Biomass Resources”.

1. Which of the following can be classified under solid biomass?
a) Agricultural residues
b) Waste water
c) Industrial effluents into rivers
d) Plastic

Answer: a
Clarification: Agricultural residues can be classified under solid biomass resource. Waste water and polluted rivers are not solids. Plastic is not a biomass.

2. What are energy crops?
a) Crops grown to remove insects
b) Crops grown to be used in generating energy
c) Crops grown to feed people
d) Crops that produce energy

Answer: b
Clarification: Energy crops are crops that are grown with the specific intention to generate energy. They don’t produce energy by themselves but they are used to generate energy or serve as fuel. Eg. – bioethanol.

3. Which of the following are examples of energy crops?
a) Banyan
b) Mango
c) Herbaceous and woody
d) Apple and herbaceous

Answer: c
Clarification: Herbaceous and woody crops are examples of energy crops. Like agricultural crops are grown to feed, energy crops are grown specifically to be used as an energy resource.

4. What are herbaceous crops?
a) Insecticides
b) Rice
c) Agricultural fertilizers
d) Agricultural byproducts

Answer: d
Clarification: Herbaceous crops are plants that do not have much wood and has green and soft stems. Generally, they are agricultural byproducts like columbine. Sometimes, crops like potatoes are solely grown to produce energy.

5. Which of the following are examples of woody biomass?
a) Fallen trees due to natural disasters
b) Mint
c) Columbine
d) Agricultural byproducts

Answer: a
Clarification: Woody biomass are basically forestry byproducts, by product of management and restoration of forests, etc. Fallen trees due to a natural disaster is an example of woody biomass. Other examples are leaves, trunks, etc.

6. Which of the following are examples of lipids?
a) Sugar
b) Palm oil
c) Glucose
d) Cellulose

Answer: b
Clarification: Palm oil is an example of lipids. Other examples are soybean oil, rapeseed oil, wax, animal fat, etc. Glucose is an example of sugar.

7. Which of the following can be used to replenish nutrients in soil?
a) Steel
b) Soda
c) Biomass ash
d) Coal ash

Answer: c
Clarification: Biomass ash can be used as a soil amendment to help replenish nutrients. Coal ash cannot be used for the same because it contains toxic metals. Steel and soda are not used to replenish soil’s nutrients.

8. Which of the following is an example of short rotation coppice?
a) Maize
b) Wheat
c) Corn
d) Willow

Answer: d
Clarification: Willow is an example of short rotation coppice (SRC). It is a forestry residue. Corn, maize and wheat are examples of herbaceous crops.

9. Algae are used as feedstocks for bioenergy.
a) True
b) False

Answer: a
Clarification: Algae are used as feedstocks for bioenergy. They use sunlight to create biomass containing key components like lipids, proteins and carbohydrates. They include microalgae, macroalgae like seaweed and cyanobacteria or blue-green algae.

10. Which of the following found in municipal waste can be used as biomass?
a) Agricultural residue
b) Kitchen waste
c) Residential garbage
d) Plastic covers

Answer: b
Clarification: Kitchen waste can be used as a resource for biomass. Residential garbage and plastic covers cannot be used directly. Agricultural residue is not found in municipal waste.

11. Land fill is an example of wet waste.
a) False
b) True

Answer: b
Clarification: Land fill is an example of wet waste. It consists of residential wastes, industrial wastes and other wastes from sewage. It also consists of manure in the form of animal wastes.

12. __________ wastes are used as methane boosters.
a) Agricultural
b) Forestry
c) Industrial
d) Municipal

Answer: c
Clarification: Many industrial wastes are used as methane boosters due to their extremely high methane potential. Agricultural, municipal and forestry wastes are not suitable for methane boosters.

13. __________ biomass is used for waste water treatment.
a) Agricultural
b) Industrial
c) Municipal
d) Aquatic

Answer: d
Clarification: Aquatic biomass in the form of micro-organisms are used for waste water treatment. They operate in anaerobic environment during the treatment.

14. Which of the following parameters is used to define sustainability of biogas feedstock?
a) Heating value
b) Calorific value
c) C:N ratio
d) Thermal voltage

Answer: c
Clarification: Carbon to nitrogen (C:N) ratio is one of the most important parameters used to talk about the sustainability of the biogas feedback. Heating and calorific value are parameters to describe the available fuel in a given biomass.

15. Which of the following is not a biomass resource?
a) Animal wastes
b) Forestry residue
c) Agricultural residue
d) Sunlight

Answer: d
Clarification: Sunlight is not a biomass resource. Animal wastes, forestry residue and agricultural residue are biomass resources. They are used to generate energy either by combustion or bio-chemical processes.

Renewable Energy Multiple Choice Questions on “Hydrogen Energy – 1”.

1. Which of the following supplies maximum amount of hydrogen gas?
a) Natural gas
b) Anaerobic Digestion
c) Wastewater treatment
d) Electrolysis
Answer: a
Clarification: All the four options produce hydrogen gas. However, fossil fuels, specifically natural gas is the major producer of hydrogen gas. Biomass and biogas are the also commonly used to produce hydrogen gas.

2. In terms of green house gas emissions, how good or bad is hydrogen fuel?
a) Major contributor of greenhouse gas emissions
b) Zero-emission fuel
c) Lowest contributor of greenhouse gas emissions
d) Hydrogen cannot be used as fuel
Answer: b
Clarification: Hydrogen fuel is a clean source of energy. It is a zero-emission fuel burned with oxygen and is used in different applications to generate electricity. Among all sources of energy, burning fossil fuels produces maximum amount of greenhouse gases.

3. Which of the following use hydrogen as fuel?
a) Fossil fuels
b) Anerobic digestion
c) Fuel cells
d) Cooking
Answer: c
Clarification: Fuel cells and internal combustion engines used hydrogen as fuel cells. Anaerobic digestion requires biomass in the form of waste water to generate electricity. Though fossil fuels contain hydrogen atoms, they do not require external supply of hydrogen as fuels. Cooking does not require hydrogen as fuel.

4. Which of the following is the most popular application of hydrogen fuel cell?
a) Fuel cell vehicles
b) Fuel cell energy power plants
c) Fuel cells stand-alone power supplies
d) Fuel cells spacecraft
Answer: d
Clarification: Spacecraft propulsion uses hydrogen as fuel with the help of fuel cells. It is one of the most established techniques to deploy spacecrafts into outer-space. Though fuel cell vehicles are becoming popular, they are not well established yet.

5. How is hydrogen gas produced from fossil fuels?
a) Partial oxidation of methane
b) Electrolysis
c) Evaporation
d) Biomass gasification
Answer: a
Clarification: Hydrogen gas is produced from fossil fuels by different techniques like partial oxidation of methane, steam reforming and coal gasification. Biomass gasification and electrolysis produce hydrogen gas in small quantities.

6. What is the major drawback of steam-methane reforming technique to produce hydrogen?
a) Capital intensive
b) Releases greenhouse gases into atmosphere
c) A niche technology
d) Poor efficiency
Answer: b
Clarification: The steam-methane reforming technique is the current leading technology to produce hydrogen. However, the main drawback of steam-methane reforming technique is that it releases greenhouse gases, carbon dioxide and carbon monoxide into the atmosphere.

7. How does electrolysis produce hydrogen?
a) By running electricity to combine hydrogen and water
b) By separating water into hydrogen and oxygen and generating electricity
c) By passing electricity into water to separate it into hydrogen and oxygen
d) By passing electricity into water to evaporate it into hydrogen
Answer: c
Clarification: Electrolysis is one of the cleanest techniques to produce hydrogen. Electricity is passed through water to separate it into oxygen and hydrogen. In electrolysis, electricity is not generated and instead is used to perform a chemical reaction

8. Why is hydrogen hazardous as fuel?
a) Because of high ignition and low combustion energy
b) Because of high ignition and high combustion energy
c) Because low ignition and low combustion energy
d) Because of low ignition and high combustion energy
Answer: d
Clarification: Hydrogen is extremely dangerous as fuel. This is because hydrogen has a low ignition temperature and releases large amounts of energy during burning – high combustion energy. Also, it is hard to store as it tends leak easily from storage tanks.

9. Traditionally, why is steam methane reforming preferred over electrolysis?
a) Because electrolysis requires electricity
b) Because electrolysis has lower production efficiency
c) Because steam methane reforming produces greenhouse gases
d) Because electrolysis produces greenhouse gases
Answer: a
Clarification: Traditionally, steam methane reforming preferred over electrolysis. This is simply because electrolysis requires electricity. Currently, producing electricity is expensive. As the cost of producing a unit of electricity becomes cheaper, electrolysis will be favoured over steam methane reforming because it does not release greenhouse gases.

10. What is the main problem in using hydrogen as fuel for vehicles?
a) Capital intensive
b) Storage
c) Fuel cell technology is not well established
d) Cars will become heavy
Answer: b
Clarification: The main problem in using hydrogen as fuel for vehicles is storage of hydrogen. Hydrogen is difficult to store because it leaks easily. Moreover, it is extremely hazardous as fuel due to its low ignition temperature and high combustion energy.

11. What is a fuel cell?
a) Converts heat energy to chemical energy
b) Converts heat energy to electrical energy
c) Converts chemical energy to electrical energy
d) Converts kinetic energy to heat energy
Answer: c
Clarification: A fuel cell works just like a battery. It converts chemical energy to electrical energy. The chemical energy from a redox reaction occurring within the cell is converted to electrical energy due to the flow of electrons.

12. How does hydrogen fuel cell work?
a) Membrane → hydrogen ions → electric current and recombination with oxygen
b) Electric current and recombination with oxygen → hydrogen ions → membrane
c) Hydrogen ions → membrane → electric current and recombination with oxygen
d) Recombination with oxygen → electric current → membrane → hydrogen ions
Answer: d
Clarification: The hydrogen ions in one chamber of the cell flow into the other chamber through a membrane to recombine with oxygen. Since this is a redox reaction, electric current is generated due to flow of electrons.

13. What does hydrogen fuel cell emit?
a) Water
b) Steam
c) Greenhouse gas
d) Methane
Answer: a
Clarification: Hydrogen fuel cell produces water – its only emission. It does not release any greenhouse gases or carbon compounds like methane because the reaction occurs with two substances, hydrogen and oxygen.

14. Fuel cell vehicle is sourced by a battery.
a) True
b) False
Answer: b
Clarification: A fuel cell vehicle (FEV) or a fuel cell electric vehicle (FCEV) is sourced by a fuel cell. It may work in combination with a battery to supply sufficient power to run the systems. But the source of the energy is a fuel cell.

15. High pressure containers are used to store hydrogen.
a) True
b) False
Answer: a
Clarification: Hydrogen is stored in a variety of ways to prevent hazards. One of them is by using high pressure containers. Another commonly used technique is cryogenics – low temperatures.

Renewable Energy Multiple Choice Questions on “Energy Scenario in India – 1”.

1. In terms of total primary energy consumption, India stands _______
a) third
b) second
c) first
d) fifth
Answer: a
Clarification: In terms of total primary energy consumption, India stands third globally. United States and China are the two countries ahead of India.

2. Where is the largest coal belt in India?
a) Uttar Pradesh
b) Jharkhand
c) Assam
d) Kerala
Answer: b
Clarification: The largest coal belt in India is at Jharia located in the Dhanbad neighbourhood in the state of Jharkhand. Jharia is famous for its rich coal resources used to make coke.

3. Which of the following majorly account for thermal power in India?
a) Oil
b) Solar thermo-mechanical systems
c) Coal and lignite
d) Biomass
Answer: c
Clarification: Coal and lignite account for 67% of India’s installed capacity. The electricity sector in India had an installed capacity of over 250 GW by the end of July 2014. Solar thermo-mechanical systems are renewable systems and are not amongst the major contributors.

4. When (year) was India the third largest electricity producer in the world?
a) 2019
b) 2010
c) 2017-18
d) 2014-15
Answer: d
Clarification: India was the third largest electricity producer in the world during 2014-15. However, only 80% of the population had access to mains power.

5. Which of the following is a non-commercial form of energy used for cooking in India?
a) Cow dung
b) Coal
c) Hydro
d) Electricity
Answer: a
Clarification: Cow dung is a non-commercial form of energy used for cooking in India. It comes under the category of biomass and is burnt to generate energy for cooking. Coal, hydro and electricity are commercial forms of energy.

6. What is the largest thermal power plant in India?
a) Mundra Thermal Power Station
b) Vindhyachal Thermal Power Station
c) Sasan Ultra Mega Power Plant
d) Talcher Super Thermal Power Station
Answer: b
Clarification: Vindyachal Thermal Power Station in the Singrauli district of Madhya Pradesh is the largest power plant in India. It has an installed capacity of 4760MW. It is a coal based plant and is operated by NTPC.

7. What is the second largest thermal power plant in India?
a) Tiroda Thermal Power Plant
b) Vindhyachal Thermal Power Station
c) Mundra Thermal Power Station
d) Talcher Super Thermal Power Station
Answer: c
Clarification: Mundra Thermal Power Station located in Kutch district of Gujarat is the second largest thermal power plant in India. It has a capacity of 4260 MW. Vindhyachal Thermal Power Station is the largest one.

8. Which of the following states is known oil reserves?
a) Jharkhand
b) Odisha
c) Madhya Pradesh
d) Assam
Answer: d
Clarification: Assam, Gujarat, Nagaland and Rajasthan are known for their oil reserves. Jharkhand, Madhya Pradesh and Odisha are known for coal reserves.

9. Which of the following states is known for gas reserves?
a) Nagaland
b) Odisha
c) Maharashtra
d) Jharkhand
Answer: a
Clarification: Nagaland, Assam, Rajasthan, etc. are known for their gas reserves. Most states containing oil reserves also contain gas reserves. Jharkhand and Odisha are known for their coal reserves.

10. _______ is found in coastal Odisha, Kerala and Andhra Pradesh.
a) Uranium
b) Thorium
c) Coal
d) Gas
Answer: b
Clarification: Thorium is found in coastal Odisha, Kerala and Andhra Pradesh. Though coal is found in Odisha and Andhra Pradesh, it is not found in Kerala. Uranium is mainly found in Jharkhand and Rajasthan.

11. _______ is the largest windfarm in India?
a) Vindhayachal
b) Mundra
c) Muppandal
d) Talcher
Answer: c
Clarification: Muppandal is the largest windfarm in India. Vindhyachal, Mundra and Talcher are names of thermal power stations which operate on coal.

12. Where is Muppandal Windfarm located in India?
a) Assam
b) Andhra Pradesh
c) Kerala
d) Tamil Nadu
Answer: d
Clarification: Muppandal windfarm is located in Tamil Nadu. It has a capacity of 1500 MW and is the largest wind power plant in India.

13. In 2017, India ranked _______ in coal consumption.
a) second
b) third
c) First
d) Fifth
Answer: a
Clarification: In 2107, India ranked second after China in coal consumption. Energy for more than half of the commercial sector is supplied by coal in India.

14. India has 22 nuclear reactors in operation.
a) True
b) False
Answer: a
Clarification: India has 22 nuclear reactors in operation in 7 nuclear plants. The total installed capacity is 6780 MW.

15. India is a net energy importer.
a) True
b) False
Answer: a
Clarification: India is a net energy importer to meet 45% of its total primary energy. India ranked third in oil consumption with 221 million tons in 2017 after USA and China.

Solar Energy Multiple Choice Questions on “Solar Water Heater”.

1. What is solar water heater?
a) Use solar energy to heat water
b) Use solar energy to generate current which is then used to heat water
c) Use water to generate heat
d) Use solar energy to generate steam
Answer: a
Clarification: Solar water heater is a system that converts sunlight into heat. This heat is then used to heat water. As the water gets heated, steam may be produced but the purpose of solar water is to heat water and not produce steam. It does not generate current.

2. Which of the following determines complexity and size of solar water heating system?
a) Food
b) Changes in ambient temperature
c) Chemicals
d) Solar radiation constant
Answer: b
Clarification: Changes in ambient temperature during day-night cycle is one of the factors that determines the complexity and size of solar water heating system. Food, chemicals and solar radiation constant does not influence the complexity and size of the system.

3. What is freeze protection in a solar water heating system?
a) Ensures that the system is frozen
b) Prevents the operation of drainback system
c) Prevents damage to system due to freezing of transfer fluid
d) Ensures that the transfer fluid is frozen
Answer: c
Clarification: Freeze protection in a solar water system prevents the system being damaged due to freezing of transfer fluid. It does not prevent the operation of drainback system.

4. What are drainback systems in solar water heating system?
a) The system that reverses the direction of flow of transfer fluid
b) The system that tracks the sun
c) The system that pumps excess transfer fluid
d) The system that drains the transfer fluid
Answer: d
Clarification: Drainback systems are systems that drain the transfer fluid particularly to ensure freeze protection. This prevents the freezing of transfer fluid and any unwanted damage to the system.

5. How does freeze-tolerance work?
a) By expansion of pipes carrying transfer fluid
b) By compression of pipes carrying transfer fluid
c) By increasing the temperature of pipes carrying transfer fluid
d) By increasing the pressure inside pipes carrying transfer fluid
Answer: a
Clarification: Freeze-tolerance works by expansion of pipes carrying the transfer fluid. The low pressure pipes are made of silicone rubber that expands on freezing.

6. Which of the following metals are used to make pipes of low cost solar water heating system?
a) Gold
b) Copper
c) Polymer
d) Silver
Answer: b
Clarification: Copper is used to make pipes of low cost solar water heating systems. Though silver and gold are good thermal conductors they are expensive. Polymer is not a metal.

7. Direct solar water heating systems ______
a) offer great overheating protection
b) are called pumped systems
c) offer no overheating protection
d) offer great freeze protection
Answer: c
Clarification: Direct solar water heating systems are also called compact systems. They offer little or no overheating protection unless they have a heat export pump.

8. How is the heat transferred from transfer fluid to potable water in indirect solar water heating systems?
a) By directly exposing the substance to sunlight
b) By using an electrical heater
c) By circulating potable water through the collector
d) By using heat exchanger
Answer: d
Clarification: An indirect solar water heating system uses a heat exchanger to transfer heat from the transfer fluid to the potable water. It does not expose the transfer fluid directly to the sunlight and does not use an electrical heater.

9. How is water heated in a direct solar water heating system?
a) By circulating potable water through the collector
b) By directly exposing water to sunlight
c) By using convection from a different transfer fluid
d) By using heat exchanger
Answer: a
Clarification: In a direct solar water heating system, the potable water is the transfer fluid. Hence, it is heated by circulating through the collector. Indirect solar water heating systems use a heat exchanger.

10. Passive systems rely on heat-driven convection.
a) False
b) True
Answer: b
Clarification: Passive systems rely on heat-driven convection. If not, they also use heat pipes to circulate the working fluid through the collector and heat it. Hence, they are cheap and are easily maintained.

11. Which of the following is an example of direct solar water heating system?
a) Pressurised antifreeze system
b) Pumped systems to circulate transfer fluid
c) Convection heat storage system
d) Drainback system
Answer: c
Clarification: Convection heat storage system is similar to an integrated collector storage system. Both these systems are examples of direct solar water heating systems.

12. How is the heat transfer fluid (HTF) heated in bubble pump systems?
a) By subjecting the closed HTF circuit to high pressure
b) By subjecting the closed HTF circuit to high pressure and by increasing the volume
c) By subjecting the closed HTF circuit to low pressure and by decreasing the volume
d) By subjecting the closed HTF circuit to low pressure
Answer: d
Clarification: In a bubble pump system, the heat transfer fluid circuit is subjected to a low pressure. This causes the liquid to boil at low temperatures as the sun heats it. The volume is not changed.

13. Batch collectors reduce heat loss by thermally insulating the storage tank.
a) True
b) False
Answer: a
Clarification: Batch collectors reduce heat loss by thermally insulating the storage tank. This is done by covering the tank in a glass-topped box that allows heat from sun to reach the water tank and traps it – greenhouse effect.

14. Overheat protection is done by passing hot water through collector during night.
a) False
b) True
Answer: b
Clarification: Overheat protection is done by passing hot water through collector during night or when there is less sunlight. This is extremely effective in direct or thermal store plumbing and ineffective in evacuated-tube collectors.

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