SCIENCE

Electrical Energy – Sources, Features, Generations And Units

Electrical Energy is the work done by the moving streams of the electrons or charges. Electrical energy is the form of kinetic energy because it produces by the movement of the electrical charges. The faster the movement of charges the more the energy they carry.

Features And Importance of Electrical Energy

(i) Convenient form – Electrical energy is a very convenient form of energy. It can be easily converted into other forms of energy. For example, If you want to convert electrical energy into heat, the only thing to be done is to pass electrical current through a wire of resistance e.g.. heater. Similarly, electrical energy can be converted into light.

(ii) Easy control – The electrically operated machines have simple and convenient starting, control and operation. For instance, an electric motor can be started or stopped by turning on or off a switch. Similarly, with simple Arrangements, the speed of electric motors can be easily varied over the desired range

(iii) Greater flexibility – One important reason for preferring electrical energy is the flexibility that it offers. It can be easily transported from one place to another with the help of conductors.

(iv) Cheapness – Electrical energy is much cheaper than other forms of energy. Thus it is overall economical to use this form of energy for domestic commercial and industrial purposes

(v) Cleanliness – Electrical energy is not associated with smoke, fumes or poisonous gases. Therefore, its use ensures cleanliness and healthy conditions.

Generation of Electrical Energy

The conversion of energy available in different forms in nature into electrical energy is known as generation of electrical energy. Energy is available in various forms from different natural sources such as pressure head of water, chemical Energy of fuels, nuclear energy of radioactive substances etc. All these forms of energy can be converted into electrical energy by the use of suitable arrangements.

Sources Of Electrical Energy

(i) The Sun – The Sun is the primary source of energy. The heat energy radiated by the Sun can be focussed over a small area by means of reflectors. This heat can be used to raise steam and electrical energy can be produced with the help of turbine-alternator combination. However, this method has limited application because:

(a) it requires a large area for the generation of even a small amount of electric power.

(b) it cannot be used in cloudy days or at night.

(c) it is an uneconomical method.

Nevertheless, there are some locations in the world where strong solar radiation is received very regularly and the sources of mineral fuel are scanty or lacking. Such locations offer more interest to the solar plant builders.

(ii) The wind – This method can be used where wind flows for a considerable length of time. The wind energy is used to run the wind mill which drives a small generator. In order to obtain the electrical energy from a wind mill continuously, the generator is arranged to charge the batteries. These batteries supply the energy when the wind stops. This method has the advantages that maintenance and generation costs are negligible. However, the drawbacks of this method are

(a) variable output,

(b) unreliable because of uncertainty about wind pressure and

(c) power generated is quite small.

(iii) Water – When water is stored at a suitable place, it possesses potential energy because of the head created. This water energy can be converted into mechanical energy with the help of water turbines. The water turbine drives the alternator which converts mechanical energy into electrical energy. This method of generation of electrical energy has become very popular because it has low production and maintenance costs.

(iv) Fuels – The main sources of energy are fuels viz., solid fuel as coal, liquid fuel as oil and gas fuel as natural gas. The heat energy of these fuels is converted into mechanical energy by suitable prime movers such as steam engines, steam turbines, internal combustion engines etc. The prime movers drives the alternator which converts mechanical energy into electrical energy Although fuels continue to enjoy the place of chief source for the generation of electrical energy, yet their reserves are diminishing day by day. Therefore. the present trend is to harness water power which is more of less a permanent source of power.

(v) Nuclear energy – Towards the end of Second World War, it was discovered that large amount of heat energy is liberated by the fission of uranium and other fissionable materials.

Units of Electrical Energy

The capacity of an agent to do work is known as its energy. The most important forms of energy are mechanical energy, electrical energy and thermal energy. Different units have been assigned to various forms of energy.

(i) Mechanical energy – The unit of mechanical energy is newton-metre or joule on the M.K.S or SI system. The work done on a body is one newton-metre (or joule) if a force of one newton moves it through a distance of one metre ie.

Mechanical energy in joules = Force in newton X distance in metres

(ii) Electrical energy – The unit of electrical energy is watt-sec or joule and is defined as follows: One watt-second (or joule) energy is transferred between two points if a p.d. of 1 volt exists between them and 1 ampere current passes between them for 1 sec i.e.,

Electrical energy in watt-sec (Or joules) =voltage in volts x current in amperes x time in seconds

(iii) Heat – Heat is a form of energy which produces the sensation of warmth. The unit of heat is calorie, British thermal unit (B.Th.U) and centigrade heat units (CH.U.) on the various systems Calorie.

It is the amount of heat required to raise the temperature of 1 gm of water through 1°C i.e..

1 calorie =1 gm of water x 1°C 

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