Page 60 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

MODULE 3 : Heating Effect, Cells and Batteries

LESSON 13-19 : Chemical effects faraday law of electrolysis,

heating joulet low cells & batteries

Objectives

At the end of this lesson you shall be able to:
• state the chemical effect of electrical current, law’s of electrolysis
• state the basic principle of electroplating
• state the principle and construction of primary & secondary cells
• explain charging methods, care & maintenance of batteries
• state heating of electric current & Joules law
• state principle & operation of solar cell.

Electricity is one of today’s most useful source of energy. Electricity in motion is called electric current. Electricity
almost used necessity in modern equipment and machinery. Electricity does not move is called static electricity.
Eg: Attraction of paper to the comb.
When an electric current flows through a circuit various effects are produced, such as
• Chemical Effect.
• Heating Effect.
• Magnetic Effect.
• Special ray effect.
• Shocking effect.
Chemical effects of electric current
When an electric current is passed through a conducting liquid (electrolyte) it is decomposed into its constituents
due to chemical action.

Electrolysis
The process of decomposing liquids by the passage of electric current through the liquid is called electrolysis
For electrolysis to work, the ions must be free to move. The atom which loses or gains an electron and thus
possesses electric charge is called an ion. Ions are free to move when an ionic substance is dissolved in water
or when melted.
Here is what happens during electrolysis

• Positively charged ions move to the negative electrode during electrolysis which are known as cations. They
receive electrons and are reduced.
• Negatively charged ions move to the positive electrode during electrolysis which are known as anions. They
lose electrons and are oxidized.
The conduction of electric current through an electrolyte together with the resulting chemical changes is called
electrolysis.
When DC is passed through water it decomposes into hydrogen and oxygen.
Terms and defenitions
Electrolyte

Electrolyte is a solution or paste capable of conducting an electric current because of its dissociation into positive
and negative ions.

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