Anna University 2 Marks Questions and Answers

7. Energy Sources

 

1. Define mass defect.

The difference between the calculated and experimental masses of nucleus is called mass defect. It is denoted by ∆m.

∆ m={ Total mass of the protons, neutrons and electron } – { Experimental mass of the nucleus }

 

2. What is binding energy?

Binding energy is defined as the energy released when a given number of protons and neutrons coalesee to form nucleus.

 

3. Define nuclear energy.

The energy released by the nuclear fission (or) nuclear fusion, is called nuclear energy.

 

4. What are the drawbacks of nuclear energy. (A.U. June 2014)

(i) The nuclear radiation can damage the structure of cells in the human body.

(ii) It causes diseases like cancer and blindness.

(iii) It causes genetic disorder in a human body.

(iv) It causes sterility in young generation.

(v) It causes serious pollution problems

(vi) Disposal of nuclear waste is the biggest problem.

 

5. Which isotope of uranium is used in nuclear reactor? (A.U.T Coim July 2010)

U²³⁵₉₂

 

6. What are the general components of a nuclear reactor? (TCY AU Jan 2008)

1. Fuel rods

2. Control rods

3. Coolents

4. Moderaters

5. Pressure vessel

6. Protective shield

7. Turbine

 

7. What is a nuclear reactor?

The arrangement or equipment used to carry out fission reaction under controlled conditions is called a nuclear reactor.

 

8. What is light water nuclear - power plant?

Light-water nuclear-power plant is the one, in which U²³⁵ fuel rods are submerged in water. Here the water acts as coolant and moderator.

 

9. What are moderators. Give some examples.

The substances used to slow down the neutrons are called moderators.

Examples

Ordinary water, Heavy water, Graphite, Beryllium.

 

10. What are Coolants? Give example. (A.U:T TNV June 2011)

In order to absorb the heat produced during fission, a liquid called coolant is circulated in the reactor core. It enters the base of the reactor and leaves at the top. The heat carried by out-going liquid is used to produce steam.

Example:

Water (act as moderator & coolant), heavy water, liquid metal (Na or K), air (CO₂).

 

11. What is the major role of pressure vessel in the nuclear reactor?

It withstand the pressure as high as 200 kg/cm².

 

12. What is fissile nucleides and fertile nucleides? (A.U Jan 2013)

(i) The fissionable nucleides such as U²³⁵ & Pu²³⁹ are called fissile nucleides.

(ii) The non-fissionable nucleides such as U²³⁸ & Th²³² are called fertile nucleides.

 

13. What is Breeder reactor? (Chen & TNV AU Jan 2009) (A.U Jan 2013)

Breeder reactor is the one which converts non-fissionable material (U²³⁸, Th²³²) into fissionable material (U²³⁵, Pu²³⁹).

 

14. What is meant by Solar energy conversion. How is it done?

Solar energy conversion is the process of conversion of direct sunlight into more useful forms. This solar energy conversion occurs by the following two mechanisms.

1. Thermal conversion.

2. Photo conversion.

 

15. What is thermal conversion?

Thermal conversion involves absorption of thermal energy in the form of IR radiation. Solar energy is an important source for low-temperature heat (temperature below 100°C), which is useful for heating buildings, water and refrigeration.

 

16. Define photo conversion.

Photo conversion involves conversion of light energy directly into electrical energy.

 

17. What is photogalvanic cell (or) Solar cell. (Coim AU Jan 2008) (A.U Jan 2013)

Photogalvanic cell is the one, which converts the solar energy (energy obtained from the sun) directly into electrical energy.

It consists of a p-type semiconductor (such as Si doped with B) and n-type semiconductor (such as Si doped with P). They are in close contact with each other.

As the solar energy is available freely and also it is pollution free, in future its utility is very important.

 

18. Explain the applications of solar cells.

1. Solar cells are used in calculators, electronic watches, radios and TVs.

2. Solar cells are superior to other type of cells, because these are non-polluting and eco-friendly.

3. Solar energy can be stored in Ni-Cd batteries and lead-acid batteries.

4. Solar cells can be used to drive vehicles.

5. Solar cells, made of silicon, are used as a source of electricity in space craft and satellites.

 

19. What is wind energy. How is it obtained?

(or)

Write how wind energy is generated. (A.U. Dec 2015)

Moving air is called wind. Energy recovered from the force of the wind is called wind energy. The energy possessed by wind is because of its high speed. The wind energy is harnessed by making use of wind mills.

 

20. What are the drawbacks of wind energy.

1. Public resists for locating the wind farms in populated areas due to noise generated by the machines and loss of aesthetic appearance.

2. Wind farms located on the migratory routes of birds will cause hazards.

 

21. What are the merits of wind energy? (Coim A.U Feb 2010)

(i) It does not cause any air pollution.

(ii) It is very cheap and economic.

(iii) It is renewable.

(iv) It does not cause any pollution

 

22. Write any four methods adopted for harnessing wind energy? (CBE. A.U. Jan 2009)

(a) Sky sail.

(b) Ladder mill.

(c) Kite ship (Large free flying sails).

(d) Sky wind power (Flying electric generator).

(e) Briza technologies (Hovering wind turbine).

(f) Sequoia automation (The kite wind generator).

 

23. Name any three highly invesigated solar cell materials.

1. Crystalline Si

2. Thin films

3. Next generation Perovskite Solar Cells (PSCs)

 

24. Define geo-thermal energy.

The energy harnessed from the high temperature present inside the earth is called geothermal energy.