4.3 Properties Of Materials

1) Different materials have different properties or characteristics as follows:

• conduct electricity
• conduct heat
• float in water
• absorb water
• can be stretched
• allow light to pass through

2) Materials that conduct electicity
    (a) A material that allows electricity to pass through it conducts electricity.
    (b) Objects made of metals, such as copper, iron and steel, can conduct
         electricty. Wires are made of copper (a metal) which can conduct electricity.
    (c) Carbon is a non-metal that can conduct electricity. Other non-metals
          cannot conduct electricity.

3) Materials that conduct heat
    (a) Materials that allow heat to flow from one part of an object to another
         conduct heat.
    (b) Objects made of metals can conduct heat easily. Metals such as steel and
          aluminium are used as cooking utensils to conduct heat quickly.
    (c) Non-metals, such as wood, rubber, leather, glass and plastic, do not conduct
        heat and electricity.
    (d) Materials that conduct heat can also conduct electricity.

The bulbs light up because the wires conduct electricity.

 

The pan conducts heat to the food quickly.

 

 

 

4) Materials that float in water
    (a) Objects that are made of wood and plastic can float in water.
    (b) They do not sink when put in water.
    (c) Objects made of glass, metal, cloth and clay sink in water.

Objects that float or
sink in water.



5) Materials that absorb water
    (a) Materials such as wood and cloth absorb water.
    (b) Objects such as a tissue and a towel become wet when they come
         into contact with water. These objects can be used to wipe wet surfaces.
    (c) Objects made of glass, metal, clay, rubber and plastic cannot absorb water.
         Water droplets can be seen on their surfaces when they come into contact
         with water.
    (d) Materials that do not absorb water are used to make waterproof objects
          such as umbrelas, raincoats and tents. These objects stop us from getting
          wet.

6) Materials that can be stretched
    (a) Objects made of rubber can be pulled and stretched.
    (b) These objects retutn to its original shape and size when released. They are
          elastic.
    (c) Examples of objects that can be stretched are rubber bands and springs.

A rubber band can be stretched.










7) Materials that allow light to pass through
    (a) Glass and certain types of plastics allow light to pass through them. An
          object can be seen if placed behind such materials.
    (b) Wood, metal and rubber do not allow light to pass through them. Objects
          cannot be seen if placed behind them.