Wednesday, May 15, 2013

Electricity sources

Introduction :

Electricity is the main branch of physics, which deals with the motion of the charges. The device which produce electricity or which can convert one form of energy into another form is called the sources of electricity.The sources of elecricity can be had from nuclear plant,  fossil fuels like coal, natural gas etc. Even the solar radiation can be used to obtain electricity.Here we discuss the sources of electricity.

About Electricity sources

Electricity is the very important form of energy, which we use, in our daily life. Now these days we even do not imagine the life in the absence of electricity. The sources of electricity are cells, which are very common and very convenient in use. There are two types of the cells one are called the primary cells and t0he other are called the secondary cells. The primary cells are those, which cannot be recharged, and the secondary cells are recharged several times up to some limit. Voltaic cell is the most important type of the source of electricity.

It is the simplest form of the electrochemical cell. It consists of a glass vessel containing dil. sulphuric acid. Copper and the zinc rod are dipped in the dil. Sulphuric acid. These copper and zinc rods are called the electrodes. When the bulb of a torch is connected across the electrodes through a conducting wire, it glows that means the electricity is produced due to some chemical reaction. When sulphuric acid dissolved in water, it decomposes into ions as shown in the reaction given below

H2SO4       `->`         2H+ + SO4 2-

Zinc atoms from zinc plate begin to dissolve slowly in H2SO4 in form of Zn2+. Each zinc atom dissolved in H2SO4 from the Zn plates leaves two electrons on the Zn plate. This zinc plate becomes negatively charged.

Zn (in solution)        `->`        Zn 2+   + 2e- (on Zn plate)

The potential acquired by the Zn plate is – 0.62 Volt. When Zn ions enter the solution from the Zn plate, an equal number of H+ leaves the solution and deposit on the copper plate. The hydrogen ions get electrons from the copper plate to become neutral hydrogen atoms.

H+ + e -    `->`            H

A pair of hydrogen atom combines to form the hydrogen molecule and the bubbles of the hydrogen gas are formed. Copper plate becomes positively charged and the potential is 0.46 Volt. So the potential difference of the voltaic cell is 0.46 – (-0.62) = 1.08 Volts.

Conclusion of the electricity sources

Thus, we observed that the same potential difference is developed across the plates of the cell. That means there are some free charges, which are in motion. As we connect a resistance in the path of the free charges, it will move and the electricity is produced so that the current flows through the bulb and it will glow.

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