The National Programme on Technology Enhanced Learning (NPTEL) was initiated by seven Indian Institutes of Technology (Bombay, Delhi, Kanpur, Kharagpur, Madras, Guwahati and Roorkee) also the Indian Institute of Science, Bangalore in 2003 NPTEL NCER Assignment 6 answers. It consists of Five core disciplines were identified, namely, civil engineering, computer science and engineering, electrical engineering, electronics and communication engineering and mechanical engineering and 235 courses in web/video format were developed in this phase.
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The main goal of NPTEL Phase II (2009-14) was to build on the engineering and core science courses launched previously in NPTEL Phase I. so 600 web and video courses were created in all major branches of engineering, physical sciences at the undergraduate and postgraduate levels and management courses at the postgraduate level. Several improvements such as indexing of all video and web courses and keyword search were implemented.
Source- https://nptel.ac.in/about_nptel.php
This course looks at the operating principle of a range of non-conventional energy resources, materials used, characterization, and key performance characteristics. The technologies looked at will include, Solar energy, Wind, Batteries, Fuel cells, and Geothermal conversion. The advantages and limitations of these technologies in comparison to conventional sources of energy will also be examined.
Nptel mainly consists of 12-week courses. Every week NPTEL provides video lectures as well as different study materials. Every week one quiz is provided. Each quiz has a specific time deadline. After the end of time, deadline NPTEL provides a solution of that quiz as well as provides marks obtained by the registered candidate. Out of 12 assignments, only the top 8 assignment marks are considered. Weightage of assignment marks is 40 %.
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1) In modern cities, most people are carrying solar-powered devices.
Solution – False
2) In 1980s most people carried portable energy devices.
Solution – False
3) Lasers used for surgery are often on for only a very small fraction of a second at a time.
Solution – True
4) Optical microscopes have resolution in the range of microns.
Solution – True
5) Artificial pacemakers typically use Lead acid batteries.
Solution – False
6) Household bulbs use power in the range of Watts.
Solution – True
7) At the present rate of usage of energy, without changing the source of energy, it is likely that amount of carbon dioxide in the atmosphere will double in less than 100 years..
Solution – True
8) Large fraction of the energy used by the world comes from fossil fuels.
Solution – True
9) Modern oil wells have been around for less than 200 years.
Solution – True
10) The price of crude oil takes into account the time and effort that went into creating it in nature.
Solution – False
1) Increases in GDP appear linked to increases in energy usage.
Solution – True
2) Hydel power contributes to nearly half of the world energy requirements.
Solution – False
3) Biomass constitutes a significant fraction of renewable energy resources.
Solution – True
4) Nuclear power supports a very small fraction of the world energy needs.
Solution – True
5) Biomass implies burning of wood or organic matter.
Solution – True
6) Several small hydro power stations are better than one large hydro power station of the same combined capacity, from the perspective of environmental impact.
Solution – True
7) Per capita energy usage is approximately the same internationally.
Solution – False
8) The transportation sector uses the most amount of energy from amongst the various sectors.
Solution – False
9) The industrial sector uses significant amounts of energy for process heating.
Solution – True
10) China and India represent scope for significant growth for automotive sales.
Solution – True
1) There is a close link between GDP of a State and the power consumed by the state.
Solution – True
2) The CO2 in the atmosphere has been steadily decreasing in the past 60 years.
Solution – False
3) There is a strong need to change the source of energy used by the world.
Solution – True
4) Ice cores contain air that was trapped by the ice, the year the ice was formed and hence can tell us the composition of the atmosphere as a function of time.
Solution – True
5) The size of the planet decides how much energy from the sun reaches the planet, given a fixed orbit.
Solution – True
6) Energy used by mankind for the entire year reaches the surface of earth from the sun in the course of one month.
Solution – FALSE
7) A hypothetical Dyson sphere will capture all of the energy from the sun coming to the orbit of earth.
Solution – True
8) A greater fraction of the sunlight that reaches the surface of the earth falls on water..
Solution – True
9) The solar spectrum that reaches the surface of the earth is impacted by the gases in the atmosphere due to the wavelengths that they absorb.
Solution – True
10) Intensity of the radiation received from the sun is the same regardless of the distance.
Solution – False
1) The solar spectrum ranges from Violet to Red.
Answer: FALSE
2) A blackbody absorbs radiation incident on it..
Answer: TRUE
3) As the temperature of a body increases, the intensity of the radiation coming from the body increases.
Answer: TRUE
4) As the temperature of a body increases, the wavelength at which the maximum intensity occurs , increases.
Answer: FALSE
5) Humans and animals give out Infrared radiation.
Answer: TRUE
6) A flat plate collector typically does not need to track the sun across seasons since it is flat.
Answer: FALSE
7) A glass plate is used on top of the flat plate collector in order to prevent IR radiation from coming in..
Answer: FALSE
8) In order to heat air it is important to increase the area of contact between the air and the surface gathering the heat..
Answer: TRUE
9) Solar concentrators can help raise the temperature of water above 100 oC.
Answer: TRUE
10) A parabolic dish concentrator typically does not need tracking because it is curved in all directions.
Answer: FALSE
1) Metals are usually transparent because of their lack of a bandgap.
Answer: FALSE
2) Larger the bandgap the more insulating the material.
Answer: TRUE
3) The highest occupied energy level in a metal at 0 Kelvin is the Fermi Energy level.
Answer: TRUE
4) For intrinsic semiconductors, the Fermi energy is half way between the valence band and the conduction band.
Answer: TRUE
5) Fermi energy represents the chemical potential of the electrons.
Answer: TRUE
6) There is more energy in the visible part of the solar spectrum relative to the IR part of the spectrum.
Answer: FALSE
7) Direct bandgap semiconductors are better suited for solar cell applications than indirect bandgap semiconductors.
Answer: TRUE
8) The space charge region in a p-n junction is also referred to as the concentration region due to the build-up of charges there.
Answer: FALSE
9) The space charge region is always of equal width on either side of the p-n junction.
Answer: FALSE
10) Amorphous silicon is typically made using the Czochralski process..
Answer: FALSE
1) A p-n junction helps stabilize an electron hole pair.
Answer: True
2) Charge density as a function of position is constant across a p-n junction.
Answer: False
3) During forward bias, the space charge region decreases in width.
Answer: True
4) During reverse bias, the n side of the p-n junction alone is affected by the applied potential.
Answer: False
5) Without external load, when exposed to sunlight, the p-n junction is forward biased.
Answer: True
6) Recombination does not occur in a solar cell.
Answer: False
7) The maximum power point of a solar cell occurs at open circuit voltage.
Answer: False
8) The fill factor for a newly manufactured solar cell is 1.
Answer: False
9) The maximum power point of a solar cell may vary from manufacturer to manufacturer.
Answer: True
10) The Shockley- Quiesser limit suggests that a single junction solar cell has an efficiency that can reach 100% when the sun is overhead.
Answer: False
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1) During photocatalysis to split water, hydrogen and oxygen form in the same chamber.
Answer: TRUE
2) The photoelectrochemical reaction involves the flow of electrons in an external circuit.
Answer: TRUE
3) A necessary condition for single material to serve as a photocatalyst for the splitting of water is that its bandgap should be greater than the potential window corresponding to the electrolysis of water.
Answer: TRUE
4) The bandgap of a single material photocatalyst, being greater than the potential window corresponding to the electrolysis of water, is a sufficient condition for it to be used for the electrolysis of water.
Answer: FALSE
5) Bandgap of semiconducting materials can be changed by changing their particle sizes.
Answer: TRUE
6) Harnessing wind energy is an indirect way of harnessing solar energy.
Answer: TRUE
7) Windmills can cause sound pollution locally.
Answer: TRUE
8) Horizontal axis wind turbines capture energy throughout the process of rotation of the turbine.
Answer: TRUE
9) Vertical axis wind turbines do not need to be oriented with respect to wind direction.
Answer: TRUE
10) Power available in the wind increases as the square of the velocity of the wind..
Answer: FALSE
1) All the energy available in the wind can be captured using a wind turbine when the wind velocity is unaffected by the presence of the turbine.
Answer: False
2) Practical efficiencies obtained using windmills is approximately 10% to 30%.
Answer: True
3) Betz limit represents the minimum efficiency that a windmill must have to be commercially successful.
Answer: False
4) The wind velocity at the windmill is the average of the velocities well before and well after the wind mill.
Answer: True
5) Modern windmills use blades made of concrete.
Answer: False
6) Generators use permanent magnets and copper wires.
Answer: True
7) The blades of windmills experience cyclic loading and hence must have excellent fatigue properties.
Answer: True
8) It is important for the windmill blades to be stiff.
Answer: True
9) In drag type of wind turbines, the tip speed ratio can be greater than 1.
Answer: False
10) Two blade horizontal axis wind turbines experience uneven forces due to the presence of the tower.
Answer: True
1) Temperature deep inside the ocean is relatively unchanged by the time of the day.
Answer: TRUE
2) The difference in temperature that is being tapped using the OTEC system is of the order of 120oC.
Answer: FALSE
3) OTEC based systems are low in efficiency, but can be abundantly tapped.
Answer: TRUE
4) There is a boundary between mixed up water at the top of the ocean and undisturbed water deep inside the ocean.
Answer: TRUE
5) Cool water from deep inside the ocean can be directly used for Air Conditioning.
Answer: TRUE
6) Low boiling point liquids can be used in a closed cycle to run turbines using the temperature difference between warm and cold sea water.
Answer: TRUE
7) Geothermal systems try to tap the solar energy trapped by the earth.
Answer: FALSE
8) The composition of the earth can be determined in part from information on how earthquake waves travel through the earth.
Answer: TRUE
9) Biomass is non-renewable since it involves burning of wood.
Answer: FALSE
10) Use of biomass represents the capture and release of the same amount of carbon, and hence is considered safe for the environment..
Answer: TRUE
1) Batteries that have the same voltage, use the same reactants internally.
Answer: FALSE
2) Batteries help in moderating the difference between demand and supply across the day by storing and releasing energy as required.
Answer: TRUE
3) Primary batteries can be recharged several hundred times typically.
Answer: FALSE
4) Electrolytes must have good electronic conductivity in order to complete the circuit and enable the battery to function.
Answer: FALSE
5) The electrode reactions that occur during discharge are reversed during recharging in a secondary battery.
Answer: TRUE
6) In the standard electrochemical series, the potential corresponding to the Hydrogen electrode is set to 0 V arbitrarily.
Answer: TRUE
7) Lithium metal was used as the anode in early version of rechargeable Lithium based batteries.
Answer: TRUE
8) When batteries of different capacities and sizes are each discharged from their fully charged state using C/5 rate, they take the same amount of time to discharge.
Answer: TRUE
9) Charging at 6C rate means a fully discharged battery will be charged in ____10_____ min.
Answer: 10
10) If a cell has an open circuit voltage of 1.5 V and 6 of these are connected in parallel, the open circuit voltage of the battery is _____1.5________ V.
1) Fuel cells are energy storage devices.
Answer: FALSE
2) An SOFC operates at approximately 70 oC.
Answer: False
3) PEFCs uses gases as reactants.
Answer: True
4) Partial oxidation, used for reforming fuels, is an exothermic process.
Answer: True
5) Flow fields are necessary to distribute reactants across the active area of the fuel cells.
Answer: True
6) Under constant current mode of operation, the degradation of a fuel cell may be expressed in mA/h.
Answer: False
7) The voltage of the stack is ___1.2_______V.
Answer 1.2
8) The power from the stack is ___18_________ W.
Answer: 18
9) If the operating point of the fuel cell is 0.6 V, the overpotential losses are ___0.63______ V.
Answer: 0.63
10) If the impedance (ohmic) due to the membrane and contact resistance of the cell is 0.01Ω and the current in the cell is 15 Amps the polarization losses due to reasons other than ohmic are __0.48_____ V.
Answer: 0.48
1) Gas diffusion layers enable reactants from channel areas to reach land areas.
Answer: True
2) Gaskets form an essential part of the fuel cell build to prevent overboard leak.
Answer: TRUE
3) Capacitors store energy using ions.
Answer: False
4) Super capacitors have infinite cycle life.
Answer: False
5) Energy stored in a flywheel increases as the cube of the angular velocity.
Answer: False
6) Magneto hydrodynamic power generation uses the plasma state of matter.
Answer: True
7) The charge stored in it is _____0.96_____μ C.
Answer: 0.96
8) If the distance between the electrode is reduced by a factor of 2, with everything else being same , the new value of capacitance is _2.4___________
Answer: 2.4
9) The energy stored in it increase by a factor of ___12_______.
Answer: 12
10) Assuming it is a solid cylinder, it should made thinner by a factor of _ 3_______ to regain its original moment of inertia.
Answer: 3
[signinlocker id=”694″] You Can Download all assignment question in a single pdf – Assignment (1-12) in single PDF[/signinlocker]
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You can also read – assignment 5 answers
You can also read – Assignment 11 answers
Note- This is not an official answer (NPTEL NCER) provided by NPTEL. There may be some wrong answers. So Please submit your answer according to the use of your presence of mind.
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