Energy Class 10 | SEE Physics Notes

Energy:

Energy: The Capacity of doing work is called Energy.

• Its SI unit is Joule(J).

Source of Energy:

• Renewable source of energy.
• Non-Renewable source of energy, etc.

Renewable source of energy and non-renewable source of energy:

Sun: The sun is the ultimate source of energy. It provides us with heat and light energy by the process of nuclear fusion or thermal fusion.

• The nuclear fusion is a process in which light nuclear are fused and gives a single large nucleus with energy.
• Skeleton: 
  
• In the case of the sun, hydrogen nuclei are combined from the helium nucleus with an enormous amount of heat. The sun has 74% hydrogen.
• 1H¹+1H¹+1H¹+1H¹→2He⁴+2He⁴+1e°+1e°+Energy.
• The nuclear fusion is called thermonuclear fusion because it takes place at a very high temperature.

Nuclear Energy/ Thermonuclear energy:

Definition: The energy obtained by fusion or fission of nuclear is called Nuclear energy or thermonuclear energy. This process takes place at a very high temperature.

• It has two types:
  a)Nuclear fusion
  b)Nuclear fission, etc.

Nuclear Fusion	Nuclear Fission
The nuclear fusion is a process in which two or more light nuclei are fused and a single large nucleus with an enormous amount of heat produced.	The nuclear fission is a process with a large nucleus is decomposed into many small nuclei and an enormous amount of heat.
Skeleton:	Skeleton:

 Mass-Energy Reaction Theory:

• It is given by Albert Einstein.
• E=mc²
  where,
  E=Energy released
  m=mass
  c=velocity of light (3×10⁸m/s)
• Nuclear fusion and fission, both are based on the mass-energy relation of Einstein.

The alternate source of energy:

Definition: The substitute for non-renewable energy is called the Alternate source of energy. The alternate source of energy is the renewable source of energy. These are the following:

• Biogas.
• Solar energy
• Wind power
• Hydropower
• Geothermal energy
• Nuclear energy (Nuclear fusion and Nuclear fission)
• Tidal energy, etc.

Hydropower:

Definition: The power produced by the current of water is called Hydropower and used to produced electricity.

• The electricity produced from water is called Hydroelectricity. The current of water is used to rotate a turbine.
• Diagram:
  

Geothermal Energy:

Definition: The energy obtained by heat energy available inside the earth is called Geothermal Energy.

• The energy heat is used to heat water. The water converted into steam. The steam is used to rotate a turbine. when a turbine is rotated, electricity is produced.
• Diagram:
  

Tidal energy:

Definition: The energy obtained by tides of the sea or ocean is called tidal energy.

• The water of tribes is collected in the dam and its kinetic energy is used to produced hydroelectricity.

Energy Crisis: 

Definition: The problem created by the exhaustion of fossil fuel reserves due to excessive use is called energy crisis. It is a global problem.

Control of energy crisis:

• By avoiding unnecessary use of electricity.
• By conserving the existing source of energy.
• By producing and using more hydro-electricity.
• By developing the alternating source of energy, etc.

Essay: Tourism in Nepal
Population problems in Nepal

Answer the following questions:

1. What is the primary and secondary source of energy?
   Ans: The source of energy which can be used in the same form in which they present naturally are called the primary source of energy.
   The source of energy which is obtained from the primary source is called the secondary source of energy.
2. What is renewable energy? Give some examples.
   Ans: The source of energy which can be obtained again and again when one exhausted is called the Renewable source of energy.
   Examples: Biogas, Nuclear fuel, etc.
3. What is the Nonrenewable source of energy? Give some examples.
   Ans: The source of energy which can’t be obtained when exhausted is called the Non-Renewable source of energy.
   Examples: Fossil fuel, Petrochemical, etc.
4. What is a fossil fuel? Give some examples.
   Ans: The source of energy which can be obtained by dead decayed plants and animals of millions of years ago is called a fossil fuel.
   Example: Coal, petrol, etc.
5. What is hydro-power? Mention its advantages.
   Ans: The power produced by the power of water is called Hydropower.
   Its advantages are:
   a) It is pollution free.
   b) It is a renewable source of energy.
   c) It transforms from one form to another.
   d) It operates on modern devices, etc.
6. What is the energy crisis? What is the various way to solve the problem of the energy crisis?
   Ans: The problem created by the exhaustion of fossil fuel reserves due to excessive use is called energy crisis.
   The various way to solve the problem of the energy crisis is given below:
   a)By avoiding unnecessary use of electricity.
   b)By conserving the existing source of energy.
   c)By producing and using more hydro-electricity.
   d)By developing the alternating source of energy, etc.
7. What is the alternate source of energy? What is the various alternate source of energy?
   Ans: The substitute for non-renewable energy is called the Alternate source of energy. The alternate source of energy is the renewable source of energy.
   The various source of alternate energy is given below:
   a)Biogas,
   b)Solar energy, etc.
8. What is Biogas? How is it obtained?
   Ans: Biogas is produced from organic matter which can be used as an energy source. It can be obtained from animal dung.
9. What is the advantage of biogas?
   Ans: The advantage of biogas are given below:
   a)It doesn’t produce smoke.
   b) It can be used for cooking food.
   c) It is a renewable source of energy, etc.
10. What is nuclear fuel? What are the various types of nuclear reactions?
    Ans: The elements which produce a large amount of energy as a result of nuclear reactions are nuclear fuels.
    The various types of nuclear reactions are given below:
    a)Nuclear fission
    b)Nuclear fusion, etc.
11. Mention advantage of nuclear energy.
    Ans: Advantage of nuclear energy are given below:
    a) A small amount of nuclear energy produces a huge amount of energy.
    b) It is used by few, so it can be alternate energy, etc.
12. What is wind energy? Mention its advantages.
    Ans: The energy which contains wind at high speed is called wind energy.
    Its advantages are:
    a)It is free of cost.
    b) It is a renewable source of energy.
    c) It can be used to generate electricity.
    d) It provides energy without depleting energy, etc.
13. What is geothermal energy? Mention its advantages.
    Ans: The energy obtained by heat energy available inside the earth is called Geothermal Energy.
    Its advantages are given below:
    a) It supplies energy without pollution.
    b) It is a perpetual source of energy.
    c) It can generate electricity, etc.
14. What is solar energy? Write its uses?
    Ans: The energy obtained from the sun is called Solar energy.
    Its uses are:
    a) For drying clothes.
    b) For preserving fruits.
    c) For providing heat and light to the earth.
    d) For obtaining heat and light energy, etc.
15. What are the two natural processes of obtaining geothermal energy?
    Ans: The two natural process of obtaining geothermal energy are given below:
    a)Volcanic eruption.
    b)Hot water spring, etc.

Read: Pressure Notes for SEE and Force notes for SEE

Give reasons:

1. Wind energy is the outcome of solar energy.
   Ans: Wind energy is the outcome of solar energy because the heat of the sun causes the air of one planet to be heated. The hot air being lighter rises up and a vacant place is created. The cooler air from other places moves towards such vacant with great speed.
2. Biofuel and fossil fuel is the outcome of solar energy.
   Ans: Biofuel and fossil fuel is the outcome of solar energy because plants convert solar energy into chemical energy and store it in their body. The biomass of plants and animals are used as biofuel. When plants and animals of million years ago died and got buried under the soil, they were converted into fossils.
3. Hydroelectricity is the outcome of solar energy.
   Ans: Hydroelectricity is the outcome of solar energy because Iceberg is melt due to the heat of solar energy then it follows in high that is used to produce electricity.
4. Mineral oil is a fossil fuel.
   Ans: Mineral oil is a fossil fuel because mineral oil is formed from dead bodies buried millions of years ago.
5. Biogas is the best energy source in Nepal.
   Ans: Biogas is the best energy source in Nepal because Nepal is based on agriculture, so dung produce from animals is used to produce biogas.
6. Production of hydroelectricity should be encouraged.
   Ans: Production of hydroelectricity should be encouraged because the production cost of hydroelectricity is high at the beginning, after that it will be run for a long time and produces heat.