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Conduction of Electricity
Similar to many solids, some liquids also
electricity to pass through them are called
conductors; such as silver, gold, acidic
solution, salt solution, etc.
Insulator: Substances which do not allow
electric current to pass through them are
called insulators; such as plastic, rubber, etc.
Use of a circuit tester: To test whether
the material is a good electrical
Example of a circuit tester
Step 1: Set up the
circuit tester as shown
Step 2: Place the object
between the open ends of
the wire or crocodile
If the bulb lights up, it
means the material allows
electric current to flow
through the closed circuit.
The brighter the bulb,
the better the conductor
of electricity is the
Good conductor and Bad
Substances which allow electric current to pass through them
easily are called good conductors of electricity; such as silver,
gold, aluminium, etc.
Some substances allows electric current to pass through them but
in very little amount. Therefore, such substances called bad
conductors of electricity, rather than being called as insulator.
In fact, most of the substances allow electric current to pass
through them under certain conditions, so instead of using terms
conductors and insulators, good conductors and bad conductors
Electrical conductors are materials that allow electric current
to flow through.
salt water, metals such as copper, aluminium and
non-metals like graphite (a form of carbon).
are materials that do not allow
electric current to flow through.
plastics, wood, rubber, glass.
Testing of conduction of electricity through
Liquids; which contain salt dissolved in them; conduct electricity. The
conduction of electricity through a liquid can be tested using two electrodes
and a bulb.
But the conduction of electricity through the liquids which are poor conductor
cannot be tested. But conduction of electricity through such liquids can be
tested using LED or magnetic compass needle.
For this, you need a compass needle, an empty matchbox, two electric cells,
some wires, a plastic bottle cap and the liquid which is to be tested. Keep the
compass needle inside the empty tray of matchbox and wrap a couple of
rubber bands around it. Connect the wires to the battery and insert two wires
in the liquid which is kept in the plastic bottle cap. You will observe that when
the current flows through the wire, there is deflection in the compass needle.
This shows that the given liquid conducts electricity. In fact, magnetic
compass needle can detect even feeble current. LED can also be used in place
of compass needle.
Salts; dissolved in water are responsible for conduction of
electricity through water. Tap water, acid solutions, basic
solutions, etc. are good conductors of electricity. Distilled water is
poor conductor of electricity because in no salt is present in
the liquid tested.
If the bulb lights up, a
closed circuit is formed,
allowing current to flow
The liquid is a
conductor of electricity.
Some liquids are good conductors of electricity.
Example :- tap water, salt solution, hydrochloric acid, sodium
(solutions of acids, bases and salts are conductors of electricity)
Some liquids are poor conductor of electricity .
Example :- distilled water, sugar solution, kerosene, spirit etc.
Chemical Effects of Electric
When electric current is passed through a conducting solution,
some chemical reaction takes place.
Example: (a) When electric current is passed through water, water
dissociates into hydrogen and oxygen. Hydrogen is deposited over
negative pole and oxygen is deposited over positive pole.
Deposition of hydrogen and oxygen at different poles is visible in
the form of bubbles.
(b) When electric current is passed through the solution of a metal
salt, such as solution of copper sulphate, metal gets deposited at the
negative pole, because metal is positively charged.
(c) Sometimes, the colour of solution also changes when electric
current passes through it.
The above examples are some of the chemical effects of electric
current. The chemical reaction depends upon the type of solution
Electroplating is one of the chemical effects of electric current.
Electroplating is a chemical process using which a metal is coated
with a layer of another desired metal. Electroplating is done to make
the metals shiny. Electroplating is done over the articles made of
iron to make the iron shiny and to prevent iron from getting rusted.
Wheel rims, handle of cycle, etc. are made shiny by the method of
Process of electroplating:
In the process of electroplating, metal salt solution is taken in a
container. Salt of metal is chosen which is to be coated over
another metal. Metal which is to be coated is dipped in the
solution and connected with negative pole. Metal for desired
coating is connected with positive pole.
When electric current is passed through the solution, metal from
anode is dissolved in the salt solution and deposited over the
negative pole (cathode). Thus, coating of desired metal is obtained
on another metal.
Use of electroplating:
(a) Water pipes, which are made of iron, are coated with a
layer of zinc metal by the process of electroplating. Zinc is
less reactive than iron and thus prevents the iron pipe from
(b) Rims of wheel of cycle, cars, etc. are electroplated with
chromium metal. Layer of chromium metal give them shiny
appearance and prevents from rust.
(c) Ornaments made of silver or other cheap metals are
electroplated with gold to give them appearance like gold.
(d) Tin cans used for storing food are made of iron
electroplating with a coat of tin. Tin is less reactive than
iron, and prevent foods packed in them from getting spoiled.