5- Towards Green Energy | Part 1 | Science | Class 10

The blog presents the short Questions and Answers of the Chapter 5, Towards Green Energy, from Science Part 2 of Class 10 from Maharashtra State Board. These can be very useful for students preparing for SSC Board exams as well as competitive exams, as it includes the objective type basic concepts & fundamentals.

1. What are the different forms of energy ?

Ans. The different forms of energy are :
• mechanical energy
• chemical energy
• sound energy
• light energy
• heat energy.

2. On which principle are the electric power plants based ?

Ans. Most of the electric power plants are based on the principle of electromagnetic induction invented by Michael Faraday.

3. What is the principle of electomagnetic induction ?

Ans. According to this principle, whenever magnetic field around a conductor changes, a potential difference is generated across the conductor.

4. What is a electric generator?

Ans. The field around a conductor can be changed in two ways :
• if a conductor is stationary and magnet is rotating,
• if a magnet is stationary, and the conductor is moving
In both these cases a potential difference is created across a conductor. The electrical power generating machine based on this principle is called electric generator.

5. How is a turbine used in electric generator ?

Ans.
(i) Turbine is used to rotate the magnet in the generator.
(ii) A turbine has blades and when a flow of liquid or gas is directed on the blades of the turbine, it rotates because of the kinetic energy of the flow.
(iii) This turbine is connected to electric generator and thus the magnet in electric generator starts rotating and electric energy is produced.

6. What are the essential requirements to generate electricity based on the principle of electromagnetic induction ?

Ans. To generate electricity based on the principle of electromagnetic induction, we need :
(i) A generator
(ii) To rotate the generator we need a turbine
(iii) To drive the turbine, we need an energy source.

7. How is the turbine rotated in a thermal energy based power station ?

Ans. In a thermal energy based power station the turbine is rotated using steam.

8. Explain the operation of generation of electrical energy in thermal power plants ?

Ans. The operation of generation of electrical energy in thermal power plants are:

(i) First the water is heated in a boiler using the thermal energy released due to burning of coal.
(ii) Steam of very high temperature and pressure is generated and the energy in the steam drives the turbine.
(iii) Thus, the generator connected to the turbine rotates and electrical energy is produced.
(iv) The steam is converted back into water and the water is re-circulated to the boiler.
(v) Since thermal energy is used here to generate electrical energy, such power
plants are called thermal power plants.
(vi) In thermal power plants, the chemical energy in the coal is converted into electrical energy.

9. What are the problems associated with the production of electricity in thermal power plants ?

Ans. The problems associated with the production of electricity in thermal
power plants are :
(a) Burning of coal results in emission of gases like carbon dioxide, sulphur oxide and nitrogen oxide which are harmful to the health.
(b) Along with the emission of gases due to burning of coal, soot particles are also released into the environment. This may cause serious health problems related to the respiratory system.
(c) The reserves of fuel used in this method i.e. coal are limited. Therefore, in future, there will be limitations on the availability of the coal.

10. How is steam generated in nuclear power plants ?

Ans. In nuclear power plants the energy released by fission of nuclei of atoms like Uranium or Plutonium is used to generate the steam of high temperature and high pressure. This energy in the steam rotates the turbine,
which in turn drives the generator producing electricity.

11. Describe the step-by-step conversion of energy in nuclear power plants ?

Ans. In nuclear power plants :
(a) the nuclear energy is converted into thermal energy
(b) thermal energy is converted into kinetic energy of steam
(c) kinetic energy of steam is converted into kinetic energy of turbine
(d) finally the kinetic energy of the turbine is converted into electrical energy.

12. How does nuclear fission take place ?

Ans. (i) When a neutron is bombarded on atom of Uranium – 235 , it absorbs the neutron and converts into its isotope Uranium – 236.
(ii) Uranium – 236 being extremely unstable converts into atoms of Barium and Krypton through a process of fission releasing three neutrons and 200 MeV energy.
(iii) The three neutrons generated in this process cause fission of three other Uranium – 235 atoms releasing more energy.

13. What is a chain reaction ?

Ans. The neutrons released in nuclear fission reaction release more energy through fission of more uranium nuclei. This process of fission of Uranium -235 atoms continues and is called the chain reaction.

14. What are the problems associated with the production of electricity in nuclear power plants ?

Ans. The problems associated with the production of electricity in nuclear
power plants are :
(a) The products after fission of nuclear fuel are also radioactive and emit harmful radiations. The products are called as nuclear waste.
(b) An accident in nuclear power plant can be very fatal. This is because the accident may result in release of very harmful radiations.

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