Sources of energy
Question 1: What is a good source of energy?
Answer- A good source of energy should have the following qualities-
(1) It should be easily available.
(2) It should have high calorific value.
(3) It should be easy to store and transport.
(4) It should be economical.
(5) It should cause less environmental pollution.
Question 2: What is a good fuel?
Answer- A good fuel should have the following qualities-
(1) It should be easily available.
(2) It should have high calorific value.
(3) It should be easy to store and transport.
(4) It should be economical.
(5) It should cause less environmental pollution.
Question 3: If you could use any source of energy for heating your food, which one would you use and why?
Answer- We shall use LPG/CNG gas or electricity for heating our food because these are have all properties of good fuel.
Question 4: What are the disadvantages of fossil fuels?
Answer- There are following disadvantages of fossil fuels like coal and petroleum-
(1) Burning of coal or petroleum causes air pollution.
(2) Burning of fossil fuels produce gasses responsible for acidic rain and green house effect.
(3) Fossil fuels are non-renewable sources of energy.
Question 5: Why are we looking at alternate sources of energy?
Answer- Because traditional sources of energy like coal, petroleum are non renewable sources, have limited sources on earth. Also these cause pollution. So we are looking at alternate sources.
Question 6: How has the traditional use of wind and water energy been modified for our convenience?
Answer- (1) Wind energy is converted into electricity by wind mills.
(2) Energy of moving water is also converted into electricity by the use of dams and generators.
Question 7: What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?
Answer- Concave mirrors are used in soalr cooker. Because concave mirrors converge the light incident on them at a single point to produce a large amount of heat.
Question 8: What are the limitations of the energy that can be obtained from the oceans?
Answer- (1) Limitations Tidal energy-There are very few locations where dams to utilize tidal energy can be built and these cannot work all the time.
(2) Limitations of wave energy- There are limited locations with high strength waves.
(3) Limitations of Ocean thermal energy- To get electricity from ocean thermal energy OTEC plants are made.
This plant is very costly and can work only when there is temperature difference of minimum 20°C between sea level and some depth.
Question 9: What is geothermal energy?
Answer- Geothermal energy is the heat energy present inside earth in certain regions called hot spots. When underground water comes in contact with the hot spot, steam is generated. This steam is routed through a pipe to a turbine and used to generate electricity.
Question 10: What are the advantages of nuclear energy?
Answer- Electricity can be produced by nuclear fission reaction in nuclear reactor. Calorific value of nuclear sources are very high. Atomic bomb is also based on nuclear fission reaction. Sun and other stars produce a huge amount of energy by nuclear fusion reaction.
Question 11: Can any source of energy be pollution-free? Why or why not?
Answer- No, any source of energy cannot be pollution free. Solar cell like pollution free sources also produce pollution while production or destruction.
Question 12: Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer- Hydrogen is cleaner fuel than CNG because on burning hydrogen produce only water, but CNG produce green house gasses. Beside this hydrogen’s calorific value is very high.
Question 13: Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer- Solar, water and wind energy are renewable sources because these cannot be exhausted. Bio-mass and wood are also renewable sources of energy as these can be replenished again in some time.
Question 14: Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer- Coal and petroleum are two exhaustible sources of energy. These fuels were formed over millions of years ago and there are only limited reserves. If we continue to use them as at present, these reserves will be exhausted very soon.
EXERCISE QUESTION-ANSWERS
Question 1: A solar water heater cannot be used to get hot water on
(a) a sunny day (b) a cloudy day✓ (c) a hot day (d) a windy day.
Question 2: Which of the following is not an example of a bio-mass energy source?
(a) wood (b) gobar-gas (c) nuclear energy ✓ (d) coal
Question 3: Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
(a) geothermal energy (b) wind energy (c) nuclear energy ✓ (d) bio-mass.
Question 4: Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer-
Fossil fuels Sun
1. These are non-renewable sources of energy. 1. This is a renewable source of energy.
2. These cause pollution. 2. It do not cause pollution.
3. These will exhaust in near future. 3. It will last as the solar system exist.
4. Energy can be produced any time. 4. Energy can only be utilized at day time in sunshine.
Question 5: Compare and contrast bio-mass and hydroelectricity as sources of energy.
Answer-
Bio-mass Hydroelectricity
1. This is a renewable source of energy. 1. This is a renewable source of energy.
2. It causes pollution. 2. It do not cause pollution.
3. Energy can be produced anytime, anywhere. 3. There are limited places where hydroelectric power plants can be developed.
Question 6: What are the limitations of extracting energy from — (a) the wind? (b) waves? (c) tides?
Answer- (a) Limitations of wind energy-
(1) Initial cost of wind mill plant is very high.
(2) For proper working of will mills, speed of wind must be more than 15 km/h, but this is not possible for the whole year.
(3) There are limited places where wind mill plant can set up.
(4) A large area is required to set up a wind mill plant.
(b) Limitations of wave energy- There are limited locations with high strength waves.
(c) Limitations tidal energy-There are very few locations where dams to utilize tidal energy can be built and these cannot work all the time.
Question 7: On what basis would you classify energy sources as
(a) renewable and non-renewable?
(b) exhaustible and inexhaustible? Are the options given in (a) and (b) the same?
Answer- (a) The source of energy that replenishes in nature is known as renewable source of energy. Sun, wind,moving water, bio-mass, etc. are some of the examples of renewable sources of energy.The source of energy that does not replenish in nature is known as non-renewable source of energy. Coal, petroleum, natural gas, etc. are some of the examples of non - renewable sources of energy.
(b) Exhaustible sources are those sources of energy, which will deplete and exhaust after a few hundred years.Coal, petroleum, etc. are the exhaustible sources of energy.
Inexhaustible resources of energy are those sources, which will not exhaust in future. These are unlimited.
Bio-mass is one of the inexhaustible sources of energy.
Yes. The options given in (a) and (b) are the same.
Question 8- What are the qualities of an ideal source of energy?
Answer- An ideal source of energy should have the following qualities-
(1) It should be easily available.
(2) It should have high calorific value.
(3) It should be easy to store and transport.
(4) It should be economical.
(5) It should cause less environmental pollution.
Question 9: What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Answer- Advantages of using solar cooker-
(1) This is pollution free.
(2) Free Sun energy is utilized.
(3) It do not destroy nutrients of food.
Disadvantages-
(1) It cannot work at night or during clouds.
(2) Reflector of solar cooker must be directed towards Sun from time to time.
(3) High temperature cannot be attained.
(4) It takes a lot of time to hot the food.
Question 10: What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Answer- Environmental consequences of the increasing demand for energy-
(1) Gasses evolved during burning of fossil fuels increase green house effect.
(2) Gasses evolved during burning of fossil fuels are responsible for acidic rain.
(3) Gasses evolved during burning of fossil fuels cause air pollution.
(4) High energy demand result in deforestation, which cause less rain, soil erosion etc.
(5) Wastages of nuclear reactor are very dangerous.
Steps to reduce energy consumption-
(1) Lights and fans should be turned ‘ON’ only when needed.
(2) We should use energy efficient appliances.
(3) We should use bio-gas plant in rural area.
(4) We should use fuels which cause less pollution.
(5) We should use pressure cooker for cooking.
(6) We should use public transport instead of private vehicles.
(7) We should use cycle instead of bike.
Practice Worksheet
CBSE Class 10 Physics
Topic: Sources of Energy
Very Short Answer
Q1) How light travels?
Ans: Light travels in the straight lines.
Q2) What do you mean by the incident ray?
Ans: The ray of light which falls on the mirror surface is called the incident ray.
Q3) What is the speed of light?
Ans: The speed of the light is 3 ×108 meter per second.
Q4) What is the point of incidence?
Ans: The point at which the incident ray falls on the mirror is called the point of incidence.
Q5) What is beam of light?
Ans: A bundle of light rays is called a beam of light.
Click below to download practice worksheet for CBSE Class 10 Physics Sources of Energy Worksheet Set A
