Question 1 What are conductors? Give examples?
Question 2 What are insulators? Give examples?
Question 3 State few uses of conductors and insulators?
Question 4 Why should we wear rubber soled shoes or rubber chappals while operating electrical appliances?
Question 5 Why it is advisable to operate electric switches with dry hands?
Question 6 Why do electricians wear rubber hand gloves while working with electricity?
Question 7 The handles of tools screwdrivers and pliers used by electrician for repair work usually have plastic or rubber cover on them.Explain?
Some materials allow electric current to pass through them whereas other materials do not allow an electric current to pass through them.
Those materials which allow electric current to pass through them are called conductors. The flow of electric current is called electricity. All the metals are conductors of electricity. Silver metal is the best conductor of electricity. Copper and aluminium metals are also good conductors. Electric wires are made of copper and aluminium because they are conductors of electricity.
For example: iron, steel ,mercury, gold, metal alloys (like Steel, brass ,bronze) are conductors of electricity. All the objects made of metals or metal alloys are also conductors. The objects such as coins, keys ,pins, aluminium foil, sewing needles and iron nail are all conductors of electricity.
A non-metal called carbon (in the form of graphite) is also a conductor of electricity. The thin black core of our pencil is called pencil lead which is made of graphite and is also a conductor of electricity.
The human body conducts electricity to small extent as it is a poor conductor of electricity. A person gets electric shock on touching an uncovered electric wire carrying current because some electric current passes through his body.
Water is a poor conductor of electricity. If a person operates an electric switch with wet hands ,he can get an electric shock because water present on the wet hands can conduct some electricity from the switch into his body. We should, therefore, operate the switches of electrical appliances with dry hands.
Those materials which insulators do not allow electric current to pass through them as called insulators.
For example: rubber, plastic, ceramics , porcelain, asbestos, wood ,glass, mica ,cotton ,jute ,wax ,paper, air etc.
Rubber is an insulator ,therefore ,an eraser and balloon are also insulators.Wood is an insulator, so objects made of wood are also insulator.Plastic is an insulator ,so plastic scale, Polythene bags, nylon socks are also insulators.A candle, glass are insulators.
The outer covering of electric wire is made of plastic because plastic is an insulator. Plastic covering does not allow electric current to pass through it. When an electric switch is in the off position then air is present between the ends of wire connected to the switch. Since air is a non conductor of electricity, electricity is not conducted across the gap between the ends of the wire in the switch and hence the bulb does not light up.