Heat

Stainless steel pans are usually provided with copper bottoms. The reason for this could be that

(a) copper bottom makes the pan more durable.

(b) such pans appear colourful.

(c) copper is a better conductor of heat than the stainless steel.

(d) copper is easier to clean than the stainless steel.

A wooden spoon is dipped in a cup of ice cream. Its other end

(a) becomes cold by the process of conduction.

(b) becomes cold by the process of convection.

(c) becomes cold by the process of radiation.

(d) does not become cold.

An iron ball at 40°C is dropped in a mug containing water at 40°C.

The heat will

(a) flow from iron ball to water.

(b) not flow from iron ball to water or from water to iron ball.

(c) flow from water to iron ball.

(d) increase the temperature of both.

One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be

(a) 80°C (b) more than 50°C but less than 80°C

(c) 20°C (d) between 30°C and 50°C

In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

Look at Figure. Mark where the heat is being transferred by conduction, by convection and by radiation.

 Discuss why wearing more layers of clothing during winter

Match the following:

Fill in the blanks:

(a) The hotness of an object is determined by its __ __.

(b) Temperature of boiling water cannot be measured by a

____ thermometer.

(c) Temperature is measured in degree ___ _.

(d) No medium is required for transfer of heat by the process of ___ _.

(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of __ _ _.

(f) Clothes of ___ _ colours absorb heat better than clothes of light colours.

Give two examples each of conductors and insulators of heat.

 State similarities and differences between the laboratory thermometer and the clinical thermometer.