Chapter-09: Transfer of Heat

After studying this unit, the students will be able to:

• Recall that thermal energy is transferred from a region of higher temperature to a region of lower temperature.
• Describe in terms of molecules and electrons, how heat transfer occurs in solids.
• State the factors affecting the transfer of heat through solid conductors and hence, define the term Thermal Conductivity.
• Solve problems based on thermal conductivity of solid conductors.
• Write examples of good and bad conductors of heat and describe their uses.
• Explain the convection currents in fluids due to difference in density.
• State some examples of heat transfer by convection in everyday life.
• Explain that insulation reduces energy transfer by conduction.
• Describe the process of radiation from all objects.
• Explain that energy transfer of a body by radiation does not require a material medium and rate of energy transfer.

Multiple Choice Questions

1.	All the bodies expand _______ on heating:
	a. Variable	b. Constantly
	c. Uniformly	d. All of them
2.	Temperature is the:
	a. Mass contained by the body	b. Force of the molecules of body
	c. Degree of hotness or coldness of the body	d. None of above
3.	The SI unit of temperature is:
	a. °C	b. °F
	c. K	d. °K
4.	Temperature of 30 °C in Fahrenheit is:
	a. 86 °F	b. 80 °F
	c. 30 °F	d. 90 °F
5.	Human normal body temperature of 37 °C in Fahrenheit is:
	a. 98.6 °F	b. 98 °F
	c. 100 °F	d. None of above
6.	Boiling point of water in Fahrenheit is:
	a. 100 °F	b. 273 °F
	c. 212 °F	d. 373 °F
7.	Celsius equivalent of 0K is:
	a. -273 °C	b. -459.4 °C
	c. 0 °C	d. 100 °C
8.	Fahrenheit equivalent of 0K is:
	a. -273 °F	b. -459.4 °F
	c. 0 °F	d. 100 °F
9.	Heat is a type of _____ energy:
	a. Kinetic	b. Potential
	c. Mechanical	d. None of above
10.	Linear expansion of a rod occurs along
	a. One	b. Two
	c. Three	d. All
11.	The characteristic of unequal expansion of different metals is employed in a device known as:
	a. Thermometer	b. Burner
	c. Calorimeter	d. Thermostat
12.	Linear expansion depends on:
	a. Length of rod	b. Change in temperature
	c. Nature of material of rod	d. All of above
13.	Thermostat works on the principle of:
	a. Unequal expansion of solids	b. Pascal’s law
	c. Anomalous expansion of water	d. Vaporization
14.	Thermostat is used in:
	a. Electric iron	b. Refrigerator
	c. Fire alarm	d. All of above
15.	SI unit of Coefficient of linear & volume expansion is:
	a. m	b. K
	c. K-1	d. °C
16.	Volume expansion depends on:
	a. Volume of block	b. Change in temperature
	c. Nature of material of block	d. All of above
17.	Beta () =
	a. a	b. 2a
	c. 3a	d. 5a
18.	There are _______ type (s) of expansion (s) take place in a liquid filled in a container:
	a. One	b. Two
	c. Three	d. Four
19.	The liquid(s) used in thermometers is (are):
	a. Mercury	b. Alcohol
	c. Water	d. Both a & b
20.	Ice is a (an):
	a. Good conductor	b. Bad conductor
	c. Perfect Conductor	d. None
21.	The quantity of heat that causes IK change in temperature in a substance of mass 1 Kg is called:
	a. Specific heat	b. Latent heat
	c. Heat of exchange	d. None of above
22.	Unit of specific heat is:
	a. Jkg-1K	b. JkgK-1
	c. Jkg-1K-1	d. J
23.	Which of the following has highest specific heat?
	a. Water	b. Ice
	c. Mercury	d. Alcohol
24.	Specific heat of water is:
	a. 2100 Jkg-1K-1	b. 2500 Jkg-1K-1
	c. 3200 Jkg-1K-1	d. 4200 Jkg-1K-1
25.	Climate of regions near sea shore remains moderate due to:
	a. Greater specific heat of water	b. Less specific heat of water
	c. Low freezing point of water	d. High boiling point of water
26.	Cause of land and sea breeze is:
	a. Greater specific heat of water	b. Less specific heat of water
	c. Low freezing point of water	d. High boiling point of water
27.	The device used to measure of the specific heat of an object is:
	a. Thermometer	b. Burner
	c. Calorimeter	d. Thermostat
28.	Quantity of heat that changes one kilogram of a of solid into liquid is called:
	a. Specific heat	b. Latent heat of fusion
	c. Latent heat of vaporization	d. All of above
29.	Quantity of heat that changes one kilogram of a of liquid into gas is called:
	a. Specific heat	b. Latent heat of fusion
	c. Latent heat of vaporization	d. All of above
30.	Unit of latent heat is:
	a. Jkg-1K	b. Jkg
	c. J	d. Jkg-1
31.	Latent heat of fusion of ice is:
	a. 2,260,000 Jkg-1	b. 336,000 Jkg-1
	c. 3,260,000 Jkg-1	d. None of above
32.	Latent heat of vaporization of water is:
	a. 2,260,000 Jkg-1	b. 336,000 Jkg-1
	c. 3,260,000 Jkg-1	d. None of above

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