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
The correct option is (c).
Explanation: Nuclear energy is produced during nuclear fission and fusion. In nuclear fission, the nucleus of heavy atoms (such as uranium, plutonium) is bombarded with low-energy neutrons. Therefore, uranium atom breaks into two lighter nuclei. This reaction produces huge amount of energy. In nuclear fusion, two lighter nuclei are fused together to form a relatively heavier nuclei. This reaction produces tremendous amount of energy. These reactions can be carried out in the absence or presence of sunlight.
Which of the following is not an example of a bio-mass energy source?
(a) Wood
(b) Gobar-gas
(c) Nuclear energy
(d) Coal
The correct option is (c).
Explanation: Bio-mass Energy Source: The energy source which can be obtained from plants materials and animal wastes are called bio-mass energy source.
Wood is a plant material, gobar gas is formed from animal dung and coal is a fossil fuel obtained from the buried remains of plants and animals. Therefore, these are bio-mass products.
Nuclear energy is released during nuclear fission and fusion and produces tremendous amount of energy. Hence, nuclear energy is not an example of bio-mass energy source.
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.
The correct option is (b).
Explanation: A solar water heater requires bright and intense sunlight to function. Due to absence of sunlight on a cloudy day, solar energy is not available for the solar heater to work properly.
What are the qualities of an ideal source of energy?
A source of energy which is considered as an ideal source of energy must be economical, easily accessible, pollution free, easy to store and transport and able to produce huge amount of heat and energy on burning.
Compare and contrast bio-mass and hydro electricity as sources of energy.
Bio-mass is a renewable source of energy which is obtained from dead plants and animal wastes. It is the result of natural process. Therefore, it can be naturally refilled.
Examples: Gobar-gas, wood, etc.
Hydro-electricity is also a renewable source of energy. It is obtained from the potential energy stored in water at a height.
Example: Electricity generated at dams.
Compare and contrast fossil fuels and the Sun as direct sources of energy.
Fossil Fuels: The fuels such as coal, petroleum, natural gas etc. are the energy sources those are found under the Earth’s crust. Nowadays, these energy sources are being used in a large scale. These energy sources are limited in the nature. These are non-renewable sources of energy and require millions of years for their formation.
Solar Energy: It is a renewable and direct source of energy produced by the Sun. The Sun has been shining from several years. Solar energy is free of cost to all in a huge amount.
What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Advantages: Solar cooker requires energy of Sun to operate. Solar energy is inexhaustible renewable source of energy and free for all and available in nature in huge amount.
Disadvantages: Solar cookers are very expensive. They do not work in absence of sunlight. Therefore, on a cloudy day, it becomes useless.
The regions where days are very short or places with cloud covers round the year, have limited utility for solar cooker.
What are the limitations of extracting energy from- (a) the wind? (b) waves? (c) tides?
(a) Wind mills are used to harness wind energy. A windmill cannot generate electricity if the speed of wind is less than 15 km/h. Moreover, a large number of windmills are required, which covers a large area.
(b) To extract energy from waves, very strong ocean waves are required.
(c) It requires high tides to extract energy from tides. Moreover, the occurrence of tides depends on the relative positions of Sun, Moon, and Earth.
What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
There is a huge demand of fossil fuels due to industrialisation in all over the world. Burning of fossil fuels releases many harmful gases in the atmosphere and increases the level of green house gas content in the atmosphere. It has increased the problem of global warming.
The consumption of fossil fuels cannot be completely reduced. However, some measures can be taken such as using electrical appliances wisely and not wasting electricity. In place of using our own vehicles, public transport system with mass transit must be adopted on a large scale.
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?
(a) The source of energy that cannot be exhausted in nature is called renewable source of energy.
Examples: Sun, wind, moving water, bio-mass, etc.
The source of energy that can be exhausted in nature is called non-renewable source of energy.
Examples: Coal, petroleum, natural gas, etc.
(b) Exhaustible sources are those sources of energy, which will deplete after a few hundred years later.
Examples: Coal, petroleum, etc.
Inexhaustible resources of energy are those sources which will not deplete in future.
Example: Bio-mass.
Yes. The options given in (a) and (b) are same.
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