When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length increases, and the distant objects are clearly visible to the eyes. To see the nearby objects clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the eye lens decreases and theRead more
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length
increases, and the distant objects are clearly visible to the eyes. To see the nearby objects
clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the
eye lens decreases and the nearby objects become visible to the eyes. Hence, the human eye lens is able to adjust its focal length to view both distant and nearby objects on the retina.
This ability is called the power of accommodation of the eyes.
Traditionally, waterfalls were used as a source of potential energy which was converted to electricity with the help of turbines. Since waterfalls are few in number, water dams have been constructed in large numbers. Nowadays, hydro-dams are used in order to harness potential energy of stored water.Read more
Traditionally, waterfalls were used as a source of potential energy which was converted to electricity with the help of turbines. Since waterfalls are few in number, water dams have been constructed in large numbers. Nowadays, hydro-dams are used in order to harness potential energy of stored water. In water dams, water falls from a height on the turbine, which produces electricity.
Earlier, the windmills were used to harness wind energy to do mechanical work such as lifting/drawing water from a well. Today, windmills are used to generate electricity. In windmills, the kinetic energy of wind is harnessed and converted into electricity. The rotatory motion of the blades turns the turbine of the electric generator to generate electricity.
The fossil fuels are non-renewable sources of energy, so we need to conserve them. If we were to continue consuming these sources at such alarming rates, we would soon run out of energy.
The fossil fuels are non-renewable
sources of energy, so we need to conserve
them. If we were to continue consuming these
sources at such alarming rates, we would
soon run out of energy.
The disadvantages of fossil fuels are as follows: (a) Burning of coal and petroleum produces a lot of pollutants causing air pollution. (b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain. (c) It also causes global warming.
The disadvantages of fossil fuels are as follows:
(a) Burning of coal and petroleum produces a lot of pollutants causing air pollution.
(b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain.
Natural gas can be used for heating and cooking food because it is a clean source of energy. It does not produce huge amount of smoke on burning. Although it is highly inflammable, it is easy to use, transport, and it produces a huge amount of heat on burning.
Natural gas can be used for heating and cooking food because it is a clean source
of energy. It does not produce huge amount of smoke on burning. Although it is highly
inflammable, it is easy to use, transport, and it produces a huge amount of heat on
burning.
What is meant by power of accommodation of the eye?
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length increases, and the distant objects are clearly visible to the eyes. To see the nearby objects clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the eye lens decreases and theRead more
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length
See lessincreases, and the distant objects are clearly visible to the eyes. To see the nearby objects
clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the
eye lens decreases and the nearby objects become visible to the eyes. Hence, the human eye lens is able to adjust its focal length to view both distant and nearby objects on the retina.
This ability is called the power of accommodation of the eyes.
How has the traditional use of wind and water energy been modified for our convenience?
Traditionally, waterfalls were used as a source of potential energy which was converted to electricity with the help of turbines. Since waterfalls are few in number, water dams have been constructed in large numbers. Nowadays, hydro-dams are used in order to harness potential energy of stored water.Read more
Traditionally, waterfalls were used as a source of potential energy which was converted to electricity with the help of turbines. Since waterfalls are few in number, water dams have been constructed in large numbers. Nowadays, hydro-dams are used in order to harness potential energy of stored water. In water dams, water falls from a height on the turbine, which produces electricity.
See lessEarlier, the windmills were used to harness wind energy to do mechanical work such as lifting/drawing water from a well. Today, windmills are used to generate electricity. In windmills, the kinetic energy of wind is harnessed and converted into electricity. The rotatory motion of the blades turns the turbine of the electric generator to generate electricity.
Why are we looking at alternate sources of energy?
The fossil fuels are non-renewable sources of energy, so we need to conserve them. If we were to continue consuming these sources at such alarming rates, we would soon run out of energy.
The fossil fuels are non-renewable
See lesssources of energy, so we need to conserve
them. If we were to continue consuming these
sources at such alarming rates, we would
soon run out of energy.
What are the disadvantages of fossil fuels?
The disadvantages of fossil fuels are as follows: (a) Burning of coal and petroleum produces a lot of pollutants causing air pollution. (b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain. (c) It also causes global warming.
The disadvantages of fossil fuels are as follows:
(a) Burning of coal and petroleum produces a lot of pollutants causing air pollution.
(b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain.
(c) It also causes global warming.
See lessIf you could use any source of energy for heating your food, which one would you use and why?
Natural gas can be used for heating and cooking food because it is a clean source of energy. It does not produce huge amount of smoke on burning. Although it is highly inflammable, it is easy to use, transport, and it produces a huge amount of heat on burning.
Natural gas can be used for heating and cooking food because it is a clean source
See lessof energy. It does not produce huge amount of smoke on burning. Although it is highly
inflammable, it is easy to use, transport, and it produces a huge amount of heat on
burning.