Question

Select the group of poor conductors of heat from the following:
1. Air, water, plastic
2. Wool, wood, iron
3. Water, copper, wood
4. Air, aluminium, wool

Answer 1

Correct Answer - Option 1 : Air, water, plastic

Concept:

Conduction: 

• The heat transfer through direct physical contact is known as conduction.
• The heat is transfer takes place from the hotter end to the colder end. 
  • Heat transferred from the electric burner of a stove to the bottom of a pan is transferred by conduction. 
• Good conductors of heat allow the transfer of heat across them through conduction. 
  • Most of the metals are conductors of heat. 
• Poor conductors of heat do not allow heat to pass through them. 
  • Examples of poor conductors of heat include air, water, plastic, wood, etc. 

Explanation:

Considering the different options:

• Air, water, plastic: All are poor conductors of heat. So, this is the correct option.
• Wool, wood, iron: Iron is metal and a good conductor. Wool and wood are poor conductors. So, this option is incorrect. 
• Water, copper, wood: Water, wood are poor conductors, but copper is a good conductor. 
• Air, aluminium, wool: Air and wool are poor conductors while aluminium is a good conductor.

Correct answer Air, water, plastic

Transfer of heat in water takes place through convection.

Convection

• It is heat transfer by the movement of its molecules.
• It occurs only in fluids (liquid and gas) not in solids because solid particles can not move from one place to another.
• For example, in a pot boiling water on the stove, or in thunderstorms, where hot air rises up to the base of the clouds.
• Sea breeze and land breeze occurs due to convection.

​Air is a poor conductor and vacuum is in space. The heat from the sun raches to us through radiation. 

Radiation: 

• When electromagnetic radiation is emitted or absorbed to transfer the heat or When heat is transferred in the form of electromagnetic waves is known as radiation.
• Electromagnetic radiation includes microwaves, radio waves, infrared radiation, visible light, ultraviolet radiation, gamma rays, and X-rays.