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All questions of Thermal Expansion for EmSAT Achieve Exam
A steel tape is calibrated at 20° C. A piece of wood is being measured by steel tape at 10°C and reading is 30 cm on the tape. The real length of the wood is:
a)Equal to 30 cmb)less than 30 cmc)cannot be perdictedd)more than 30 cmCorrect answer is option 'B'. Can you explain this answer?
|
Preeti Khanna answered |
When heated the length between adjacent markings increases. Hence the actual length will be less than
30 cm.
30 cm.
When water is heated from 0° C to 20° C its volume:- a)first decreases and then increases
- b)goes on increasing
- c)remains constant up to 15°C and then increases
- d)goes on decreasing
Correct answer is option 'A'. Can you explain this answer?
When water is heated from 0° C to 20° C its volume:
a)
first decreases and then increases
b)
goes on increasing
c)
remains constant up to 15°C and then increases
d)
goes on decreasing
|
|
Pooja Shah answered |
When water is heated from 0°C, its volume decreases because its density increases and you can see this effect upto 4°C. Since the density of ice is maximum at 4°C, afterwards as the density decreases the volume increases. The main reason for this is hydrogen bond in ice gets cleaved due to the melting of ice.
Water contract on heating between the temperatures- a)0°C to 4°C
- b)0°K to 4°K
- c)0o K to 273 K
- d)0°F to 4°F
Correct answer is option 'A'. Can you explain this answer?
Water contract on heating between the temperatures
a)
0°C to 4°C
b)
0°K to 4°K
c)
0o K to 273 K
d)
0°F to 4°F
|
Geetika Shah answered |
When water is heated from 0oC, its volume decreases because its density increases and you can see this effect upto 4oC. Since the density of ice is maximum at 4oC, afterwards as the density decreases the volume increases. The main reason for this is hydrogen bond in ice gets cleaved due to the melting of ice.
The temperature for which the reading on Celsius and Fahrenheit scales are identical is- a)-273°C, -273 °F
- b)-30°C, -30 °F
- c)0 °C, 0 °F
- d)-40 °C, -40 °F
Correct answer is option 'D'. Can you explain this answer?
The temperature for which the reading on Celsius and Fahrenheit scales are identical is
a)
-273°C, -273 °F
b)
-30°C, -30 °F
c)
0 °C, 0 °F
d)
-40 °C, -40 °F
|
|
Preeti Iyer answered |
The Celsius and Fahrenheit are two important temperature scales. The Fahrenheit scale is used primarily in the United States, while Celsius is used throughout the world. The two scales have different zero points and the Celsius degree is bigger than the Fahrenheit one. There is one point on the Fahrenheit and Celsius scales where the temperatures in degrees are equal. This is -40 degree C and -40 degree F.
Can you explain the answer of this question below:Two identical rectangular strips, one of copper and the other of steel, are riveted as shown to form a bi-metal strip. On heating, the bi-metal strip will
- A:
bend with steel on the concave side
- B:
get twisted
- C:
remain straight
- D:
bend with steel on the convex side
The answer is a.
Two identical rectangular strips, one of copper and the other of steel, are riveted as shown to form a bi-metal strip. On heating, the bi-metal strip will
bend with steel on the concave side
get twisted
remain straight
bend with steel on the convex side
|
Nandini Patel answered |
On heating, the copper strip will suffer greater elongation and hence the bimetal strip will bend with the steel strip on the concave side.
[Bimetal strips are widely used in thermal switching applications such as automatic electric iron].
Which phase of matter has maximum value of temperature coefficient of cubical expansion?- a)Gaseous
- b)Solid
- c)Liquid
- d)none of these
Correct answer is option 'A'. Can you explain this answer?
Which phase of matter has maximum value of temperature coefficient of cubical expansion?
a)
Gaseous
b)
Solid
c)
Liquid
d)
none of these
|
|
Pooja Shah answered |
Gas expands more than solid and liquid because gas particles are far apart hence freely move.
The relation between coefficient of volume expansion 
and coefficient of linear expansion 
is- a)αv = 2α1
- b)α1 = 3αv
- c)αv = 3α1
- d)α1 = 2αv
Correct answer is option 'C'. Can you explain this answer?
The relation between coefficient of volume expansion and coefficient of linear expansion is
and coefficient of linear expansion isa)
αv = 2α1
b)
α1 = 3αv
c)
αv = 3α1
d)
α1 = 2αv
|
The Amazing Spider Fan answered |
This is simple,because the coefficients of linear expansion A,areal expansion B,and volume expansion G,are in the ratio of 1:2:3 i.e;
A:B:G::1:2:3
Hence,G=3A
Four cylindrical rods of different radii and lengths are used to connect two heat reservoirs at fixed temperatures t1 and t2 respectively. From the following pick out the rod which will conduct the maximum quantity of heat:- a)Radius 1 cm, length 2 m
- b)Radius 1 cm, length 1 m
- c)Radius 2 cm, length 4 m
- d)Radius 3 cm, length 8 m
Correct answer is option 'D'. Can you explain this answer?
Four cylindrical rods of different radii and lengths are used to connect two heat reservoirs at fixed temperatures t1 and t2 respectively. From the following pick out the rod which will conduct the maximum quantity of heat:
a)
Radius 1 cm, length 2 m
b)
Radius 1 cm, length 1 m
c)
Radius 2 cm, length 4 m
d)
Radius 3 cm, length 8 m
|
|
Neha Sharma answered |
The rate of heat transfer is directly proportional to the bisectional surface area of the solid and inversely proportional to its parallel length.
That is heat conduction rate say H ∝ r2
∝ 1/L
I.e ∝ r2/L
Hence the conduction would be
maximum in case in which r2/L ratio is largest.
That is heat conduction rate say H ∝ r2
∝ 1/L
I.e ∝ r2/L
Hence the conduction would be
maximum in case in which r2/L ratio is largest.
The coefficient of liner expansion of a cubical crystal along three mutually perpendicular direction is 
and 
. What is the coefficient of cubical expansion of crystal?- a)α1 + α2 + α3
- b)α1 + α2 - α3
- c)α1 - α2 - α3
- d)(α1 + α2 )/ α3
Correct answer is option 'A'. Can you explain this answer?
The coefficient of liner expansion of a cubical crystal along three mutually perpendicular direction is and . What is the coefficient of cubical expansion of crystal?
and . What is the coefficient of cubical expansion of crystal?a)
α1 + α2 + α3
b)
α1 + α2 - α3
c)
α1 - α2 - α3
d)
(α1 + α2 )/ α3
|
|
Neha Joshi answered |
Cubical expansion means there is expansion is length (a1), breadth (a2) and height (a3). Therefore the net coefficient of cubical expansion is α1 + α2 + α3.
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