Study Material and Notes of Ch 14 Chemical Effects of Electric Current Class 8th Science

Topics in the chapter

• Introduction
→ Good Conductor
→ bad Conductor
• Electrolyte
• Magnetic effect of current
• Electroplating


→ Materials, which allow electric current to pass through them, are good conductors of electricity.

→ Materials, which do not allow electric current to pass through them easily, are poor conductors of electricity.

→ Metals such as copper and aluminium conduct electricity whereas materials such as rubber, plastic and wood do not conduct electricity.

Good conductor 
Poor conductor
Lemon Juice  Coal Tar

Vinegar  Distilled Water
Acid solutions Honey
Basic solutions Vegetable oil
Salty water ( Tap water, sea water) Kerosene


→ Conducting liquids are also called electrolytes.

→ The electric current passing through a conducting liquid (electrolyte) causes chemical reactions (electrolysis).

→ A chemical reaction takes place when electric current passes through a conducting solution.

Magnetic Effect of current

→ The bulb will glow or the magnetic needle will show deflection if the liquid in the beaker is a good conductor of electricity.

→ Greater the deflection of needle or brighter the light, better is the conductivity of the liquid.

→ A greenish-blue spot on the potato around the positive electrode is seen if current is passed through wire.

→ The chemical effects of electric current are used in the working of electrochemical cells.

→ Electrochemical cells which generate current are called voltaic cells or galvanic cells.

→ Common batteries also consist of one or more such cells.


→ Electroplating is the process of coating a metal using electric current and electrolyte.

→ The above picture explains how copper can be deposited on a different metal using electroplating.

→ Electroplating can be used to give shiny and scratch proof finish (properties of chromium) to objects made from cheaper metals.

→ A coating of zinc is deposited on iron to protect it from formation of rust.

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