SORTING MATERIALS INTO GROUPS (POST -4 )

GOOD MORNING BOYS ! Welcome to another class of science.In the last class you learnt about - opaque,translucent and transparent materials and about conductors and insulators of heat.
A QUICK RECALL !( Do them orally )
Give one two examples of each of the following-
1. Translucent materials            2.Insulators of heat
3. Conductors of heat.               4. Transparent materials
5. Opaque objects                      6.Poor conductorsof heat

LEARNING OUTCOMES OF THIS CLASS
By the end of this class you will be able to-
- distinhuish between magnetic and nonmagnetic materials
-distinguish between conductors and nonconductors of electricity.

 You must have experienced that the lid of some  metallic pencil boxes close automatically when you try to close them. This is because they have a magnet in it.
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MATERIALS CAN BE GROUPED AS FOLLOWS-
Magnetic materials- These are materials like iron ,nickle ,cobalt that get atrracted by a magnet.


Nonmagnetic materials- These are materials like wood, plastic that are not attracted by a magnet.


Magnetic materials can be separated from nonmagnetic materials using strong magnets.
Magnetic materials are used in electrical and electronic devices.



Electricity is brought from the power stations to our houses  with help of cables or wires.These cables and wires are made of aluminium and copper ,because they allow electricity to pass through them.
CONDUCTORS OF ELECTRICITY- These are substances like copper,aluminium .and other metals which permit electricity to flow through them.

NONCONDUCTORS OF ELECTRICITY OR INSULATORS-
These are substances like paper,rubber,PVC,wood etc which do not permit electricity to flow through them.



-Pure water is a very poor conductor of electricity. It can be made conducting by addind small quantity of an acid, alkali or salt to it.


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HOTS!
Can plastic be used to make electric cables ?

DO THE FOLLOWING QUESTIONS IN YOUR NOTEBOK-

8. Why are electric wires made of copper and are covered with plastic ?
ans: Electric wires are made of copper so that electricity can pass through them. They are covered with plastic because plastic is an insulator and will protect us from getting an electric shock .

9. Distiguish between the following-
a) Magnetic materials                             Nonmagnetic materials
  They are materials that get               They are mterials that do not
   attracted by magnets.                       get attracted by magnets.
  eg. iron ,copper                                   eg. plastic, wood

b) Conductors of electricity              Nonconductors of electricity   Substances which permit           Substances which donot allow 
 electricity to pass through           electricity to pass through them.
 them.  eg. iron                                          eg.  plastic

THIS IS ALL FOR TODAYS CLASS! HAVE A GOOD DAY!