Electricity

 Electricity Current electricity is one of the important energy for the mankind. In our daily life we need it for different aspects. To avoid darkness at night we use electric lamps. To operate radio, T.V, telephone, computer or other electric appliances, we need current electricity. Similarly electric heater, electric iron, electric motor, etc depend on current electricity. Electricity is essential to run the factories, and various industries. Source of electricity Equipments which generate current electricity are said to be the electric sources. Electricity can be obtained by different means. Some of them are discussed below. 

1. Cell

 2. Photo cell 

3. Dynamo and generators 

1. Cell: By some specific chemical reaction current electricity is produced in the cells. For example, we have dry cells or simple cells. We get current electricity by the chemical reaction inside them. Dry cells are generally used to operate the tourch light, small transistors, etc. Dry cells are handy to carry as there is no chemical in the liquid form inside them. 

2. Photo cell: Photo cells convert solar energy into useful current electricity. Photo cells absorb the incident solar energy and convert them into current electricity. The electricity is used for lighting the bulbs, to operate T.V and computers.

 3. Dynamo and generators: Electric generators can produce a large amount of current electricity. Turbine, a component in the generator is rotated at high speed by some external means. The turbine is rotated by the impact of a current of water, or air, vapour, etc. upon the blades of a wheel. The wheel then rotates the shaft of the generator, which produces current electricity. In Nepal, water from a certain

high level is let fall on the turbine fans. The stored energy in the high speed running water is used to rotate the turbine and then the shaft, It spins the generator which finally produces electricity. Since the river sources originate from the high mountains, at high levels, its huge stored hydro energy rotates the turbine wheel and shaft, by which we get electricity. In another example a small dynamo fitted in a bi-cycle near its wheel rim can produce electricity of small magnitude. When the dynamo head is made to press against the rotating wheel, the small shaft inside it rotates and electricity is produced.

Insulator: The experimental observations show that, rubber, pebble, eraser, plastic, etc are insulators of electricity, because current electricity cannot conduct through them. We find that the cable wires are covered with insulators like rubber, plastic, etc which are insulaters of electricity. A properly insulated cable can be touched without any electric shock or danger even if electricity is flowing continuously within them. Semi-conductors: Semi-conductors are neither very good conductor nor very bad insulator. Silicon and germanium are the two best known semiconductors. Their conductivity changes on the physical conditions, as their temperature and on the added impurities on them. Pencil lead also works as a semi conductor.

Summary: 

1. Current electricity is one of the essential energy to run our daily life smoothly. 

2. Some primary sources of electricity are simple cells, photo cells, and electric generators. 

 3. The closed path of the electric circuit contains wires, switches, etc in it.

 4. The materials which electricity can easily conduct through are termed as good conductors of electricity. 

5. The materials which electricity cannot easily conduct through are termed as bad conductor of electricity.

 6. Semi-conductors show the property which lie between a conductor and an insulator. At very low temperature they behave as an insulator but at moderately high temperature they show some conducting nature.