Heat and Energy Exe-6C Long Answer Concise Physics ICSE Class-9 Selina Publishers

Heat and Energy Exe-6C Long Answer Concise Physics ICSE Class-9 Selina Publishers. There is the solutions of Long Answer type Questions of your latest textbook which is applicable in 2024-25 academic session. Visit official Website CISCE for detail information about ICSE Board Class-9

Heat and Energy Exe-6C Long Answer Concise Physics ICSE Class-9 Selina Publishers

Board	ICSE
Class	9
Subject	Physics
Writer / Publication	Concise Selina Publishers
Chapter-6	Heat and Energy
Exe-6C	Energy Sources
Topics	Solution of Exe-6(C) Long Answer Type
Academic Session	2024-2025

Exercise- 6C Energy Sources

Heat and Energy Long Answer Concise Physics ICSE Class-9 Selina Publishers

page -157

Long Answer :

Q1- What is solar energy? How is the solar energy used to generate electricity in a solar power Plant?

Ans- The energy obtained from Sun is called solar energy. A solar power plant is a device in which heat energy of sun is used to generate electricity. It consists of a large number of concave reflectors, at the focus of which there are black painted water pipes.

The reflectors concentrate the heat energy of the sun rays on the pipes due to which water inside the pipes starts boiling and produces steam. The steam thus produced is used to rotate a steam turbine which drives a generator producing electricity.

Q2- What is a solar cell? State two uses of solar cells. State whether a solar cell produces a.c. or dc. Give one disadvantage of using a solar cell.

Ans- A solar cell is an electrical device that converts light energy directly into electricity with the help of photovoltaic effect. Solar cells are usually made from semiconductors like silicon and gallium with some impurity added to it.

When sunlight is made incident on a solar cell, a potential difference is produced between its surface, due to which a current flows in the circuit connected between the opposite faces of the semiconductor.

Two uses of solar cells are as listed below:

1. They do not require maintenance and last over a long period of time at zero running cost.
2. They are very useful for remote, inaccessible and isolated places where electric power lines cannot be laid. A solar cell produces d.c. (direct current).

One disadvantage of solar cell is listed below:   (i) The initial cost of a solar panel is sufficiently high.

Q3- State two advantages and two dis advantages of producing hydro electricity.

Ans- Advantage of producing the hydro electricity:

1. It does not produce any environmental pollution.
2. It is a renewable source of energy.

Disadvantages of producing hydroelectricity:

1. Due to the construction of dams over the rivers, plants and animals of that place get destroyed or killed.
2. The ecological balance in the downstream areas of rivers gets disturbed.

Q4- What percentage of total electrical power generated in India is obtained from nuclear power plants? Name two places in India where electricity is generated from nuclear power plants.

Ans- At present only about 3% of the total electrical power generated in India is obtained from the nuclear power plants. Tarapur in Maharashtra and Narora in Uttar Pradesh are the places where electricity is produced using nuclear energy.

Q5- State two advantages and two dis advantages of using nuclear energy for producing electricity.

Ans- Advantages of using nuclear energy:

1. A very small amount of nuclear fuel can produce a tremendous amount of energy.
2. Once the nuclear fuel is loaded into nuclear power plant, it continues to release energy for several years.

Disadvantages of using nuclear energy:

1. It is not a clean source of energy because very harmful nuclear radiations are produced in the process.
2. The waste causes environmental pollution.

Q6- State four ways for the judicious use of energy.

Ans- Four ways for the judicious use of energy are:

1. The fossil fuels such as coal, petroleum, natural gas should be used only for the limited purposes when there is no other alternative source of energy available.
2. The wastage of energy should be avoided.
3. Efforts must be made to make use of energy for community or group purposes.
4. The cutting of trees must be banned and more and more new trees must be roped to grow.

Q7- What do you mean by degradation of energy? Explain it by taking two examples of your daily life.

Ans- The gradual decrease of useful energy due to friction etc. is called the degradation of energy. Examples:

1. When we cook food over fire, the major part of heat energy from the fuel is radiated out in the atmosphere. This radiated energy is of no use to us.
2. When electrical appliances are run by electricity, the major part of electrical energy is wasted in the form of heat energy.

Q8- What is wind energy? How is wind energy used to produce electricity? How much electric power is generated in India using the wind energy?

Ans- The kinetic energy of the moving large masses of air is called the wind energy. Wind energy is used in a wind generator to produce electricity by making use of wind mill to drive a wind generator. At present in India, more than 1025 MW electric power is generated using  wind energy.

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