# Topic: Thermal Properties of Matter (Test 3)

Topic: Thermal Properties of Matter
Q.1
In which mode of heat transfer no medium is required?
A. convection
B. conduction
C. none of the three
Explaination / Solution:

Heat transfer through radiation takes place in form of electromagnetic waves.

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Q.2
In which mode of heat transfer is there material movement?
B. none of the three
C. conduction
D. convection
Explaination / Solution:

Convection is the heat transfer due to bulk movement of molecules within fluids.

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Q.3
if k is the thermal conductivity of the material of the bar of cross section A whose ends are maintained at temperatures  and , the rate of flow of heat H is :
A. H=kATCTD2L
B. H=kATC+TDL
C. H=kATC+TD2L
D. H=kATCTDL
Explaination / Solution:

rate of flow of heat H depends on

hence

K =  thermal conductivity of the material

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Q.4
If is the temperature of the surrounding medium and  is the temperature of the body, then according to Newton’s Law of Cooling rate of cooling of the body is
A. dQdt=k(T22+T12)
B. dQdt=k(T2-T1)
C. dQdt=k(T2+T1)
D. dQdt=k(T22T12)
Explaination / Solution:

Newton's law of cooling states that the rate of heat loss of a body is directly proportional to the difference in the temperatures between the body and its surroundings.

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Q.5
The average kinetic energy of the molecules in a substance is most closely associated with
A. absolute zero
B. expansion
C. heat
D. temperature
Explaination / Solution:

E=32kT
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Q.6
The Celsius temperature at absolute zero is equal to
A. 273C
B. -273C
C. 100 C
D. 100 C
Explaination / Solution:

TC01000=TK273.15373.15273.15
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Q.7
Which of the following is true of the Celsius and Kelvin temperature scales?
A. A Kelvin degree is smaller in size than a Celsius degree.
B. Both the Celsius and Kelvin temperature scales have negative values.
C. A Kelvin degree is larger in size than a Celsius degree.
D. A Kelvin degree and a Celsius degree are equivalent in size.
Explaination / Solution:

A Kelvin degree and a Celsius degree means change in temperature.

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Q.8
In general, when a solid is heated, it
A. expands inversely proportionally to the change in temperature
B. expands proportionally to the change in temperature
C. contracts inversely proportionally to the change in temperature
D. contracts proportionally to the change in temperature
Explaination / Solution:

Δl=βVΔTΔA=αVΔTΔV=γVΔT
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Q.9
A brass spring has a spring constant k. When the spring is heated, the spring constant will
A. increase, then decrease
B. remain the same
C. decrease
D. increase
Explaination / Solution:

on heating spring will be expand

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Q.10
Which of the following statement(s) is/are true? (I) Every substance contains heat. (II) For heat to flow between two substances, they must be at different temperatures. (III) The internal energy of a substance is equal to the kinetic energy of the molecules in the substance.
A. I and II only
B. II only
C. II and III only
D. III only