Chemical Effects of Electric Current Class 8 PPT

 Page 1


CHAPTER - 14
CHEMICAL EFFECTS OF ELECTRIC 
CURRENT
Page 2


CHAPTER - 14
CHEMICAL EFFECTS OF ELECTRIC 
CURRENT
Conductors and insulators
• Conductors : Substances which allow electric 
current to pass through them are called 
conductors
• Insulators: Substances which does not allow 
electric current to pass through them are 
called insulators.
Page 3


CHAPTER - 14
CHEMICAL EFFECTS OF ELECTRIC 
CURRENT
Conductors and insulators
• Conductors : Substances which allow electric 
current to pass through them are called 
conductors
• Insulators: Substances which does not allow 
electric current to pass through them are 
called insulators.
Testing conductivity of substances
A conduction tester is a device used to determine whether a substance is a good 
or poor conductor of electricity.
Conduction tester using a torch bulb :-
A simple conduction tester has an electric cell and a torch bulb. One terminal of 
the cell is connected to one terminal of the bulb by a wire. The other terminal of 
the cell and bulb have wires which can be brought in contact with materials to test 
whether they are good or poor conductors of electricity.
If the material is a good conductor, the bulb glows and if it is a poor conductor 
the bulb does not glow. 
Page 4


CHAPTER - 14
CHEMICAL EFFECTS OF ELECTRIC 
CURRENT
Conductors and insulators
• Conductors : Substances which allow electric 
current to pass through them are called 
conductors
• Insulators: Substances which does not allow 
electric current to pass through them are 
called insulators.
Testing conductivity of substances
A conduction tester is a device used to determine whether a substance is a good 
or poor conductor of electricity.
Conduction tester using a torch bulb :-
A simple conduction tester has an electric cell and a torch bulb. One terminal of 
the cell is connected to one terminal of the bulb by a wire. The other terminal of 
the cell and bulb have wires which can be brought in contact with materials to test 
whether they are good or poor conductors of electricity.
If the material is a good conductor, the bulb glows and if it is a poor conductor 
the bulb does not glow. 
electric current produces magnetic 
field :
If a magnetic compass is kept near a wire and current flows through 
the wire, the magnetic needle gets deflected. So we can use a 
magnetic compass instead of a torch bulb or LED in the circuit. The  
magnetic needle gets deflected even if a weak current flows in the 
circuit.
Page 5


CHAPTER - 14
CHEMICAL EFFECTS OF ELECTRIC 
CURRENT
Conductors and insulators
• Conductors : Substances which allow electric 
current to pass through them are called 
conductors
• Insulators: Substances which does not allow 
electric current to pass through them are 
called insulators.
Testing conductivity of substances
A conduction tester is a device used to determine whether a substance is a good 
or poor conductor of electricity.
Conduction tester using a torch bulb :-
A simple conduction tester has an electric cell and a torch bulb. One terminal of 
the cell is connected to one terminal of the bulb by a wire. The other terminal of 
the cell and bulb have wires which can be brought in contact with materials to test 
whether they are good or poor conductors of electricity.
If the material is a good conductor, the bulb glows and if it is a poor conductor 
the bulb does not glow. 
electric current produces magnetic 
field :
If a magnetic compass is kept near a wire and current flows through 
the wire, the magnetic needle gets deflected. So we can use a 
magnetic compass instead of a torch bulb or LED in the circuit. The  
magnetic needle gets deflected even if a weak current flows in the 
circuit.
Electrical conductivity of solids :-
Some solids are good conductors of electricity.
Eg :- copper, steel, iron, aluminium etc.
Some solids are poor conductors of electricity.
Eg :- wood, plastic, rubber, glass etc.