KSEEB SSLC Science Solutions
Chapter 7 Sources of Energy
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Solutions for SSLC Science Chapter 7 Sources of Energy
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.
Answer: (b) a cloudy day
Solar water heater uses solar energy for heating water. In cloudy day, there is no proper sunlight and so solar energy is unavailable for solar water heater to work. Therefore, it cannot be used in cloudy day to get hot water.
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
Answer: (c) nuclear energy
Biomass is obtained from plant materials and animal waste. In above options other than nuclear energy all are obtained from plant material or animal waste.
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.
Answer: (c) nuclear energy
Nuclear energy is obtained from nuclear fission or fusion. In nuclear fission, uranium atoms are bombarded with neutrons. This causes splitting of atoms into two lighter nuclei. In nuclear fusion lighter nuclei are fused to form a heavier nuclei. High amount of energy is produced during nuclear reactions and it is carried out in absence of light or solar energy.
Stored heat energy deep inside the earth’s crust is geothermal energy. Wind movement are caused due to uneven heating of the earth’s surface. Biomass is obtained from plant materials and dead animals.
4. Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer: Fossil fuels are obtained from dead animals buried under the earth’s crust. These are non renewable sources of energy. Once used they won’t be obtained again. When compared to solar energy, it is renewable source of energy which is abundant in nature.
5. Compare and contrast biomass and hydroelectricity as sources of energy.
Answer: Biomass is obtained from plant materials and remains of animals. Biomass is renewable source of energy. Wood and gobar gas are familiar examples of biomass. Hydroelectricity is obtained from potential energy stored on height, where water is allowed to fall on turbines which ultimately produces electricity. When compared both are renewable sources of energy.
6. What are the limitations of extracting energy from— (a) the wind? (b) waves? (c) tides?
Answer: Following are the limitations of wind energy, waves and tides –
1) Limitations of wind –
- Windmills can only be established only at those places where wind blows at fast rate for maximum portion of the year.
- To maintain speed of turbine the minimum speed of wind must be 15 km / h.
- Establishing windmills require large area.
- Establishment costs is very high.
- The windmill parts need high level of maintenance because various natural factors such as rain, sun, storm, cyclone can cause corrosion and ultimately breaking of the windmill.
2) Limitations of waves – To extract energy from sea waves must be strong.
3) Limitations of tides – To extract energy from tides, very high tides are required.
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) Energy which replenishes from their own by the nature are known as renewable sources of energy. For example, solar energy, tides, waves, etc. Energy which cannot be replenish by their own are non renewable sources of energy. For example, natural gas, coal petroleum, etc.
(b) Energy that will be depleted in few hundred years is known as exhaustible sources of energy. For example, coal, petroleum, natural gas, etc. Energy that will not be depleted in future even after continuous use are inexhaustible sources of energy. For example, solar energy, tidal energy, etc.
Yes options of a and b are same.
8. What are the qualities of an ideal source of energy?
Answer: Following are some qualities of ideal sources of energy-
- It should produce large energy per unit volume
- It should be easily available
- It should be easy to store and transport
- And most importantly it should be more economical
9. What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
- Solar cooker uses solar energy which is inexhaustible and renewable source of energy
- Do not produce harmful gases to pollute environment.
- Solar cookers are costly to establish
- Cooking in solar cooker is carried out slowly
- Cooking is always done in presence of sunlight.
- Solar cooker has limited utility in cloudy weather, at places where days are shorter, in winter season, etc.
10. What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Answer: With increase in industrialization demand for sources of energy increases. To fulfill this demand fossil fuels are used as source of energy. Increase in use of fossil fuels causes harmful effects on environment like global warming. Use of fossil fuels cannot be stopped completely but it can be reduced to some extent. Avoid wastage of electricity, water,etc. Use public transport for travelling. This will help in reduce of energy consumption.
Chapter 7 -Sources of Energy