4) Explain why all electrical wires are covered with a plastic material?
Electrical wires are covered with plastic material because:
Plastic is a poor conductor (insulator) of electricity
This prevents electrical current from flowing through the covering
It protects people from electric shocks
5) A glass of steel with hot tea is difficult to hold as compared to a bone-china cup. Why?
A steel glass with hot tea is difficult to hold compared to a bone-china cup because:
Steel is a good conductor of heat (as demonstrated in Activity 10 with the metal spoon experiment)
Heat from the hot tea quickly travels through the steel to our hands
Bone-china, like other ceramic materials, is a poor conductor of heat
6) Handles of cooking utensils are made of wood or plastic. Why?
Handles of cooking utensils are made of wood or plastic because:
Wood and plastic are poor conductors of heat
This prevents the heat from the cooking vessel from reaching our hands
Example, noting that handles of pressure cookers and pans are made of wood or Bakelite plastic for this reason
7) Pure water is a bad conductor of electricity while salty water is a good conductor of electricity. Explain by giving reasons.
Pure water is a bad conductor of electricity while salty water is a good conductor because:
pure water is a poor conductor of electricity , However, when salts are dissolved in water, it becomes a good conductor
