Conductors of electricity My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited © 2009 Marshall Cavendish International (Singapore) Private Limited

Questions to think about… What are electrical conductors and insulators? Are good conductors of electricity also good conductors of heat? How do we use electricity safely? © 2009 Marshall Cavendish International (Singapore) Private Limited

What is electricity? Electricity is conducted through some things better than others do. Some materials are very resistant. Their atoms hold their electrons very tightly so they cannot move very well. These things are called insulators. (Can you give some examples?) E.g. rubber, plastic, cloth, glass, dry air etc. Some materials have loosely held electrons which move through them very easily. These are called Conductors e.g. most metals like copper, aluminium, steel etc.

Conductors and insulators Take a close look at this wire. There is metal on the inside and plastic on the outside. Why? © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Some materials, like copper, allow an electric current to flow through them. Such materials are called conductors of electricity. Many other metals also conduct electricity well. Hence, wires are usually made of metals. © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of metals that are conductors of electricity: aluminium © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of metals that are conductors of electricity: iron © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of metals that are conductors of electricity: copper © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of metals that are conductors of electricity: gold © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of metals that are conductors of electricity: silver © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators To prevent the electric current from flowing out of a circuit, wires are coated with plastic. Plastic does not allow an electric current to flow through it. plastic © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Other than plastic, many other materials do not allow an electric current to flow through them. These materials are called non-conductors of electricity. Non-conductors of electricity are also called insulators. © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of non-conductors of electricity: paper © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of non-conductors of electricity: rubber © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of non-conductors of electricity: wood © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of non-conductors of electricity: glass © 2009 Marshall Cavendish International (Singapore) Private Limited

Conductors and insulators Examples of non-conductors of electricity: clay © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Electricity is useful but it can harm us if we do not use it carefully. Other than getting a nasty shock, we can cause a fire if we do not use electricity carefully. So what can we do to protect ourselves? © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Never try to repair any electrical equipment or electrical socket yourself. Get an adult or an electrician who knows how to repair it. © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely When repairing any electrical equipment, proper tools with plastic or wooden handles should be used. Such materials are non-conductors of electricity. They prevent electricity from flowing from the equipment to our hands. © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Ensure that there are no exposed wires in electrical equipment. © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Never touch switches or electrical equipment with wet hands. © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Do not put too many plugs into one socket. © 2009 Marshall Cavendish International (Singapore) Private Limited

Using electricity safely Use safety devices such as circuit breakers and fuses. Sometimes, fires are accidentally caused when too much current flows through a circuit. Circuit breakers and fuses break a circuit when too much current flows through them. fuse circuit breaker © 2009 Marshall Cavendish International (Singapore) Private Limited

The end My Pals are Here! Science © 2008 Marshall Cavendish (Singapore) Private Limited © 2009 Marshall Cavendish International (Singapore) Private Limited