PHYSICS CH7 Heat Science - PHYSICS CH7 Heat

A device in which the loss of heat due to conduction, convection and radiation is minimized is ______.

In which mode of transfer of heat, molecules pass on heat energy to neighbouring molecules without actually moving from their positions?

SI unit of temperature is ______.

Two cylindrical rods of same length have the area of cross section in the ratio 2:1. If both the rods are made up of same material, which of them conduct heat faster?

Calorie is the unit of ______.

Assertion: When water is heated up to 100°C, there is no raise in temperature until all water gets converted into water vapour.
Reason: Boiling point of water is 10°C.

Assertion: Maximum sunlight reaches earth’s surface during the noon time.
Reason: Heat from the sun reaches earth’s surface by radiation.

Assertion: Food can be cooked faster in vessels with copper bottom.

Reason: Copper is the best conductor of heat.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false

• If assertion is false but reason is true.

Assertion (A) : When a very hot liquid is poured into a thick glass tumbler it cracks.
Reason (R) : Unequal expansion of the inner and outer glass walls causes the glass to crack.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If assertion is true but reason is false.
(d) If assertion is false but reason is true.

Assertion (A) : Heat energy is transferred from one body to another due to a
temperature difference between them.
Reason (R) : Heating a substance causes a rise in temperature.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If assertion is true but reason is false.
(d) If assertion is false but reason is true.

Define specific latent heat capacity

Define thermal capacity.

What is specific heat capacity?

Differentiate convection and radiation.

Numerical Problem.

How much heat energy is required to change 2 kg of ice at 0°C into water at 20°C? (Specific latent heat of fusion of water = 3,34,000 J/kg, Specific heat capacity of water = 4200 JKg–1K–1).

Numerical Problem.

What could be the final temperature of a mixture of 100 g of water at 90 °C and 600g of water at 20°C.

How can you experimentally prove water is a bad conductor of heat? How is it possible to heat water easily while cooking?

What are the changes of state in water? Explain.

Explain convection in daily life.

Explain the following effects of heat.
(i) Expansion
(ii) Change in temperature
(iii) Change in state
(iv) Chemical changes.

Compare heat capacity and specific heat capacity.

The fixed temperature at which matter changes state from solid to liquid is called ______.

Liquids and gases are generally ______ conductors of heat.

During day time, air blows from______ to______

The fastest mode of heat transfer is ______.

Specific latent heat L =………………………

Why do people prefer wearing white clothes during summer?

How does the water kept in an earthen pot remain cool?

Ice is kept in a double-walled container. Why?

Define conduction.

Specific latent heat