Dynamic Electricity:
It is the electricity produced due to the flow of the electric charge forming an electric current.
There are two methods to produce electric current:
1- Chemical reactions.
2- Electric generators.
First: Chemical reactions:
The simple cell:
It consists of:
a- A glass container containing dilute sulphuric acid (H2SO4).
b- Two metal plates immersed in the dilute sulphuric acid, one is copper ( +ve pole) and the other is zinc (-ve pole).
Disadvantages of simple cell:
1- Polarization:
It is the accumulation of hydrogen gas bubbles on the +ve copper pole which insulate the copper plate from the acid decreasing the electric current.
Getting rid of polarization:
a- By cleaning copper plate from time to time to remove the hydrogen gas.
b- By adding a chemical substance (manganese dioxide) to react with hydrogen.
2- The local reactions:
Its is produced due to the reaction between the impurities in Zinc plate (such as iron and lead) with the acid forming small cells which produce local currents decrease the original current because this current in an opposite direction to the original current.
Getting rid of local reactions:
Zinc plate is covered by mercury (to form Zinc amalgam) to insulate the impurities and prevent them from reacting with the acid.
3- The difficutly of transporting:
It is difficult to transport the simple cell from one place to another because it is made from glass (broken easily) and contains sulphuric acid.
Note:
In the electrical cells such as simple cell and dry cell, chemical energy is changed into electrical energy.
Second: Electric generators:
In dynamo (electric generator), kinetic energy is changed into electrical energ y.
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