Q. Why is charcoal better than wood as a fuel ?
Ans: 1. Charcoal does not produce smoke when it is burnt whereas wood produces a lot of smoke.
2. Charcoal has a higher calorific value than wood. Calorific value of charcoal is 33 Kilojoules per gram whereas that of woos is 17 kilojoules per gram.
3. Charcoal is relatively a compact fuel and hence is easier to handle.
Q. How can we overcome energy crisis?
Ans: The energy crisis can be overcame by the following methods:
1) Increase the use of renewable energy sources such as sunlight, wind, tides etc.
2) Reduce the use of non-renewable energy sources such as petroleum, coal, natural gas etc.
3) Avoid the wastage of energy such as burning street lights at daytime, using car or bike for going to a walk able distance etc.
Q.A concave reflector increases the temperature that can be obtained inside a solar cooker. Give reason.
Ans: The concave reflector (mirror) is a converging mirror which focuses all the sunlight in one point (the focus). The heat generated at that point is the greatest all the light converges there. The temperature at that point is thus higher comparatively.
Q. Why is natural gas non
Ans: Natural gas is a non-renewable resource of energy because it cannot be renewed, reused or generated again in a short period of time. It is a fossil fuel formed by the decay of remains of dead plants and animals that were buried under the earth, and takes millions of years for its formation
Q. Explain the working of nuclear reactor?
Ans: When a heavy nucleus like uranium-235 is hit with a neutron, it undergoes nuclear fission. The heavy nucleus splits into two or more lighter nuclei, releasing kinetic energy, gamma radiation and free neutrons. The released kinetic energy is converted to thermal energy. This thermal energy is used to boil water to produce pressurized steam, which will drive steam turbines to generate electricity. This is the working of nuclear reactor.
Q. What are the advantages and disadvantages of thermal power plants?
Ans: Advantages:
- It can be located near industry.
- Transportation cost will be less as they can construct near industry.
- Set up cost is less.
- Production method is easy.
Disadvantages:
- High amount of coal is used to generate steam.
- It takes a long time in set up.
- Its maintenance cost is high.
- It pollutes near by area.
Q. What is a solar cell panel? Mention two applications of it?
Ans: Solar panel is made up of large number of cells put together with the help of connecting wires in a definite pattern.
Solar panel is basically used to generate electricity using the solar energy. It produces more electrical power than one solar cell. It can be used to run electrical appliances, fans and lights or bulbs. Solar panels are also used to collect energy in the day to light the street lights on the road at night.
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