Thermal Properties of Matter Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. Two rods of the same length and diameter having thermal
conductivities K
1
 and K
2
 are joined in parallel. The equivalent thermal
conductivity of the combination is
(a) (b) K
1
 + K
2
 (c)  (d) 
2. Consider two identical  iron spheres
 
, one which
lie on a thermally insulating plate, while the other
hangs from
an insulatory thread. Equal
amount of heat is supplied to the two spheres, then
(a) temperature of A will be greater than B
(b) temperature of B will be greater than A
(c) their temperature will be equal
(d) can’t be predicted
3. A student takes 50gm wax (specific heat = 0.6 kcal/kg°C) and heats it
Page 2


PART-I (Single Correct MCQs)
1. Two rods of the same length and diameter having thermal
conductivities K
1
 and K
2
 are joined in parallel. The equivalent thermal
conductivity of the combination is
(a) (b) K
1
 + K
2
 (c)  (d) 
2. Consider two identical  iron spheres
 
, one which
lie on a thermally insulating plate, while the other
hangs from
an insulatory thread. Equal
amount of heat is supplied to the two spheres, then
(a) temperature of A will be greater than B
(b) temperature of B will be greater than A
(c) their temperature will be equal
(d) can’t be predicted
3. A student takes 50gm wax (specific heat = 0.6 kcal/kg°C) and heats it
till it boils. The graph between temperature
and time is as follows. Heat supplied to the
wax per minute and boiling point are
respectively
(a) 500 cal, 50°C
(b) 1000 cal, 100°C
(c) 1500 cal, 200°C
(d) 1000 cal, 200°C
4. Two rods of same length and area of cross-section A
1
 and A
2
 have their
ends at the same temperature. If K
1
 and K
2
 are their thermal
conductivities, c
1
 and c
2
 are their specific heats and d
1
 and d
2
 are their
densities, then the rate of flow of heat is the same in both the rods if
(a)
(b)
(c)
(d)
5. If a, ß and ? are coefficient of linear, area and volume expansion
respectively, then
(a) ? = 3a
(b) a = 3?
(c) ß = 3a
(d) ? = 3ß
6. Two spheres of different materials one with double the radius and one-
fourth wall thickness of the other are filled with ice. If the time taken
for complete melting of ice in the larger sphere is 25 minute and for
smaller one is 16 minute, the ratio of thermal conductivities of the
materials of larger spheres to that of smaller sphere is
Page 3


PART-I (Single Correct MCQs)
1. Two rods of the same length and diameter having thermal
conductivities K
1
 and K
2
 are joined in parallel. The equivalent thermal
conductivity of the combination is
(a) (b) K
1
 + K
2
 (c)  (d) 
2. Consider two identical  iron spheres
 
, one which
lie on a thermally insulating plate, while the other
hangs from
an insulatory thread. Equal
amount of heat is supplied to the two spheres, then
(a) temperature of A will be greater than B
(b) temperature of B will be greater than A
(c) their temperature will be equal
(d) can’t be predicted
3. A student takes 50gm wax (specific heat = 0.6 kcal/kg°C) and heats it
till it boils. The graph between temperature
and time is as follows. Heat supplied to the
wax per minute and boiling point are
respectively
(a) 500 cal, 50°C
(b) 1000 cal, 100°C
(c) 1500 cal, 200°C
(d) 1000 cal, 200°C
4. Two rods of same length and area of cross-section A
1
 and A
2
 have their
ends at the same temperature. If K
1
 and K
2
 are their thermal
conductivities, c
1
 and c
2
 are their specific heats and d
1
 and d
2
 are their
densities, then the rate of flow of heat is the same in both the rods if
(a)
(b)
(c)
(d)
5. If a, ß and ? are coefficient of linear, area and volume expansion
respectively, then
(a) ? = 3a
(b) a = 3?
(c) ß = 3a
(d) ? = 3ß
6. Two spheres of different materials one with double the radius and one-
fourth wall thickness of the other are filled with ice. If the time taken
for complete melting of ice in the larger sphere is 25 minute and for
smaller one is 16 minute, the ratio of thermal conductivities of the
materials of larger spheres to that of smaller sphere is
(a) 4 : 5
(b) 5 : 4
(c) 25 : 8
(d) 8 : 25
7. One end of a thermally insulated rod is kept at a temperature T
1
 and the
other at T
2
. The rod is composed of two sections of length l
1
 and l
2
 and
thermal conductivities K
1
 and K
2
 respectively. The temperature at the
interface of the two sections is
(a)
(b)
(c)
(d)
8. A long metallic bar is carrying heat from one of its ends to the other end
under steady–state. The variation of temperature ? along the length x of
the bar from its hot end is best described by which of the following
figures?
(a) (b)
Page 4


PART-I (Single Correct MCQs)
1. Two rods of the same length and diameter having thermal
conductivities K
1
 and K
2
 are joined in parallel. The equivalent thermal
conductivity of the combination is
(a) (b) K
1
 + K
2
 (c)  (d) 
2. Consider two identical  iron spheres
 
, one which
lie on a thermally insulating plate, while the other
hangs from
an insulatory thread. Equal
amount of heat is supplied to the two spheres, then
(a) temperature of A will be greater than B
(b) temperature of B will be greater than A
(c) their temperature will be equal
(d) can’t be predicted
3. A student takes 50gm wax (specific heat = 0.6 kcal/kg°C) and heats it
till it boils. The graph between temperature
and time is as follows. Heat supplied to the
wax per minute and boiling point are
respectively
(a) 500 cal, 50°C
(b) 1000 cal, 100°C
(c) 1500 cal, 200°C
(d) 1000 cal, 200°C
4. Two rods of same length and area of cross-section A
1
 and A
2
 have their
ends at the same temperature. If K
1
 and K
2
 are their thermal
conductivities, c
1
 and c
2
 are their specific heats and d
1
 and d
2
 are their
densities, then the rate of flow of heat is the same in both the rods if
(a)
(b)
(c)
(d)
5. If a, ß and ? are coefficient of linear, area and volume expansion
respectively, then
(a) ? = 3a
(b) a = 3?
(c) ß = 3a
(d) ? = 3ß
6. Two spheres of different materials one with double the radius and one-
fourth wall thickness of the other are filled with ice. If the time taken
for complete melting of ice in the larger sphere is 25 minute and for
smaller one is 16 minute, the ratio of thermal conductivities of the
materials of larger spheres to that of smaller sphere is
(a) 4 : 5
(b) 5 : 4
(c) 25 : 8
(d) 8 : 25
7. One end of a thermally insulated rod is kept at a temperature T
1
 and the
other at T
2
. The rod is composed of two sections of length l
1
 and l
2
 and
thermal conductivities K
1
 and K
2
 respectively. The temperature at the
interface of the two sections is
(a)
(b)
(c)
(d)
8. A long metallic bar is carrying heat from one of its ends to the other end
under steady–state. The variation of temperature ? along the length x of
the bar from its hot end is best described by which of the following
figures?
(a) (b)
(c) (d)
9. Two rods of same length and transfer a
given amount of heat 12 second, when they
are joined as shown in figure (i). But when
they are joined as shwon in figure (ii), then
they will transfer same heat in same
conditions in
(a) 24 s
(b) 13 s
(c) 15 s
(d) 48 s
10. In a vertical U-tube containing a liquid, the two
arms are maintained at different temperatures t
1
 and
t
2
. The liquid columns in the two arms have heights
l
1 
and l
2 
respectively. The coefficient of volume
expansion of the liquid is equal to
(a)
(b)
(c)
(d)
11. Two rods, one of aluminum and the other made of steel, having initial
length l
1
 and l
2
 are connected together to form a single rod of length
l
1
 + l
2
. The coefficients of linear expansion for aluminum and steel
are a
a
 and a
s
 and  respectively. If the length of each rod increases by the
same amount when their temperature are raised by t
0
C, then find the
Page 5


PART-I (Single Correct MCQs)
1. Two rods of the same length and diameter having thermal
conductivities K
1
 and K
2
 are joined in parallel. The equivalent thermal
conductivity of the combination is
(a) (b) K
1
 + K
2
 (c)  (d) 
2. Consider two identical  iron spheres
 
, one which
lie on a thermally insulating plate, while the other
hangs from
an insulatory thread. Equal
amount of heat is supplied to the two spheres, then
(a) temperature of A will be greater than B
(b) temperature of B will be greater than A
(c) their temperature will be equal
(d) can’t be predicted
3. A student takes 50gm wax (specific heat = 0.6 kcal/kg°C) and heats it
till it boils. The graph between temperature
and time is as follows. Heat supplied to the
wax per minute and boiling point are
respectively
(a) 500 cal, 50°C
(b) 1000 cal, 100°C
(c) 1500 cal, 200°C
(d) 1000 cal, 200°C
4. Two rods of same length and area of cross-section A
1
 and A
2
 have their
ends at the same temperature. If K
1
 and K
2
 are their thermal
conductivities, c
1
 and c
2
 are their specific heats and d
1
 and d
2
 are their
densities, then the rate of flow of heat is the same in both the rods if
(a)
(b)
(c)
(d)
5. If a, ß and ? are coefficient of linear, area and volume expansion
respectively, then
(a) ? = 3a
(b) a = 3?
(c) ß = 3a
(d) ? = 3ß
6. Two spheres of different materials one with double the radius and one-
fourth wall thickness of the other are filled with ice. If the time taken
for complete melting of ice in the larger sphere is 25 minute and for
smaller one is 16 minute, the ratio of thermal conductivities of the
materials of larger spheres to that of smaller sphere is
(a) 4 : 5
(b) 5 : 4
(c) 25 : 8
(d) 8 : 25
7. One end of a thermally insulated rod is kept at a temperature T
1
 and the
other at T
2
. The rod is composed of two sections of length l
1
 and l
2
 and
thermal conductivities K
1
 and K
2
 respectively. The temperature at the
interface of the two sections is
(a)
(b)
(c)
(d)
8. A long metallic bar is carrying heat from one of its ends to the other end
under steady–state. The variation of temperature ? along the length x of
the bar from its hot end is best described by which of the following
figures?
(a) (b)
(c) (d)
9. Two rods of same length and transfer a
given amount of heat 12 second, when they
are joined as shown in figure (i). But when
they are joined as shwon in figure (ii), then
they will transfer same heat in same
conditions in
(a) 24 s
(b) 13 s
(c) 15 s
(d) 48 s
10. In a vertical U-tube containing a liquid, the two
arms are maintained at different temperatures t
1
 and
t
2
. The liquid columns in the two arms have heights
l
1 
and l
2 
respectively. The coefficient of volume
expansion of the liquid is equal to
(a)
(b)
(c)
(d)
11. Two rods, one of aluminum and the other made of steel, having initial
length l
1
 and l
2
 are connected together to form a single rod of length
l
1
 + l
2
. The coefficients of linear expansion for aluminum and steel
are a
a
 and a
s
 and  respectively. If the length of each rod increases by the
same amount when their temperature are raised by t
0
C, then find the
ratio l
1
/( l
1
 + l
2
)
(a) a
s
/a
a
(b) a
a
/a
s
(c)
s
/(a
a 
+ a
s
)
(d) a
a
/(a
a 
+ a
s
)
12. When the temperature of a rod increases from t to t + ?t, its moment of
inertia increases from I to I + ?I. If a be the coefficient of linear
expansion of the rod, then the value of  is
(a) 2a?t
(b) a?T
(c)
(d)
13. The plots of intensity versus wavelength for three
black bodies at temperatures T
1
, T
2 
and T
3
respectively are as shown. Their temperature are
such that
(a) T
1 
> T
2 
> T
3
(b) T
1 
> T
3 
> T
2
(c) T
2 
> T
3 
> T
1
(d) T
3 
> T
2 
> T
1
14. A block of steel heated to 100ºC is left in a room to
cool. Which of the curves shown in fig., represents the
correct behaviour?
(a) A
(b) B
(c) C
(d) None of these
15. The figure shows a system of two concentric spheres of radii r
1
 and r
2
are kept at temperatures T
1
 and T
2
, respectively. The radial rate of flow of
heat in a substance between the two concentric spheres is proportional to