SUBJECT: NEET-PHYSICS COURSE: MASTER PRO ELP No.

-01 TOPIC: HEAT TRANSFER

2023-24

1. Under steady state, the temperature of a body

(1) Increases with time
(2) Decreases with time
(3) Does not change with time and is same at all the points of the body
(4) Does not change with time but is different at different points of the body

2. Which of the following cylindrical rods will conduct most heat, when their ends are maintained at
the same steady temperature
(1) Length 1 m; radius 1 cm
(2) Length 2 m; radius 1 cm
(3) Length 2 m; radius 2 cm
(4) Length 1 m; radius 2 cm

3. Rate of heat flow through a cylindrical rod is Q1. Temperatures of ends of rod are T and T2. If all
the linear dimensions of the rod become double and temperature difference remains same, it's
rate of heat flow is Q2, then :-
(1) Q1 = 2Q2 (2) Q2 = 2Q1 (3) Q2 = 4Q1 (4) Q1 = 4Q2

4. The lengths and radii of two rods made of same material are in the ratios 1 : 2 and 2 : 3 respectively.
If the temperature difference between the ends for the two rods be the same then in the steady
state. The amount of heat flowing per second through them will be in the ratio of
(1) 1 : 3 (2) 4 : 3 (3) 8 : 9 (4) 3 : 2

5. For shown situation, calculate the temperature of the common interface.

6. Calculate θ1 and θ2 in shown situation.

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7. Three identical rods of length 1m each, having cross-section area of 1cm each and made of
Aluminium, copper and steel respectively are maintained at temperatures of 12°C, 4°C and 50°C
respectively at their separate ends. Find the temperature of their common junction.
[ KCu=400 W/m-K, KAl = 200 W/m-K, Ksteel = 50 W/m-K]

8. A composite rod made of three rods of equal length and cross-section as shown in the fig. The
thermal conductivities of the materials of the rods are K/2, 5K and K respectively. The end A and
end Bare at constant temperatures. All heat entering the end A goes out of the end B, there being
no loss of heat from the sides of the bar. The effective thermal conductivity of the bar is

9. The coefficient of thermal conductivity of copper is nine times that of steel. In the composite
cylindrical bar shown in the figure what will be the temperature at the junction of copper and
steel?

(1) 75°C (2) 67°C (3) 33°C (4) 25°C

10. A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts
an amount of heat Q in time t. The metallic rod is melted and the material is formed into a rod of
half the radius of the original rod. What is the amount of heat conducted by the new rod, when
placed in thermal contact with the two reservoirs in time t?
Q Q Q
(1) (2) (3) (4) 2Q
2 4 16

11. The two ends of a metal rod are maintained at temperatures 100°C and 110°C. The rate of heat
flow in the rod is found to be 4.0 J/s. If the ends are maintained at temperatures 200°C and 210°C,
the rate of heat flow will be:
(1) 16.8 J/s (2) 8.0 J/s (3) 4.0 J/s (4) 44.0 J/s

12. The unit of thermal conductivity is:

–1 –1 –1 –1 –1 –1
(1) J m K (2) J m K (3) W m K (4) W m K

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13. Two metal rods, 1 & 2 of same length have same temperature difference between their ends, their
thermal conductivities are K1 & K2 and cross sectional areas A & A2 respectively. What is required

condition for same rate of heat conduction in them.

K1 K2 K1 K2
(1) K1 = K2 (2) K1A1 = K2A2 (3) = (4) =
A1 A2  2
1
22

14. Consider a compound slab consisting of two different materials having equal thicknesses and
thermal conductivities K and 2K, respectively. The equivalent thermal conductivity of the slab is
4 2
(1) 3K (2) K (3) K (4) 2K
3 3

15. If the coefficient of conductivity of aluminium is 0.5cal/cm-sec-°C, then in order to conduct

10cal/sec-camp in the steady state, the temperature gradient in aluminium must be
(1) 5°C/cm (2) 10°C/cm (3) 20°C/cm (4) 10.5°C/cm

16. Two identical rods of a metal are welded as shown in figure-(a), 20 cal of heat flows through them
in 4 minute. If the rods are welded as shown in figure-(b), then the same amount of heat will flow
in :

(A) 1 minute (B) 2 minute (C) 4 minute (D) 16 minute

17. Two metallic rods are connected in series. Both are of same material of same length and same
area of cross-section. If the conductivity of each rod be k, then what will be the conductivity of
the combination?
(1) 4 k (2) 2 k (3) k (4) k/2

18. A cylinder of radius R made of a material of thermal conductivity k is surrounded by a cylindrical

shell of inner radius R and outer radius 2R made of a material of thermal conductivity k,. The two
ends of the combined system are maintained at different temperatures. There is no loss of heat
from the cylindrical surface and the system is in steady state. The effective thermal conductivity
of the system is
k 1k2 1 1
(1) k1 + k2 (2) (3) (k +3k2) (4) (3k + k2 )
k 1 + k2 4 1 4

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19. The temperature drop through each layer of a two layer furnace wall is shown in figure. Assume
that the external temperature T1 and T3 ̧are maintained constant and T1>T2. If the thickness of the

layers x1 and x2 are the same, which of the following statements are correct.

(1) k1 > k2

(2) k1 < k2

(3) k1 =k2 but heat flow through material (1) is larger then through (2)

(4) k1 = k2 but heat flow through material (1) is less than that through (2)

20. A deep rectangular pond of surface area A, containing water (density = ρ, specific heat capacity=s),
is located in a region where the outside air temperature is at a steady value of –26°C. The thickness
of the frozen ice layer in this pond, at a certain instant is x.
Taking the thermal conductivity of ice as K, and its specific latent heat of fusion as L, the rate of
increase of the thickness of ice layer, at this instant would be given by :-
2
(1) 26K/pr(L-4s) (2) 26K/(ρx -L) (3) 26K/(ρxL) (4) 26K/ρr( L+4s)

21. Diagram shows a heat source 'S' and three position of heat recover (hand). The main made of heat
transfer is given as 'a', 'b' & 'c'. Choose the correct matching :-

(1) a conduction; b-convection; c - radiation

(2) b - conduction; a- convection; c - radiation
(3) a conduction; c - convection; b - radiation
(4) c - conduction ; b – radiation; a – convection

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SUBJECT: NEET-PHYSICS COURSE: MASTER PRO ELP No.-02 TOPIC: HEAT TRANSFER
2023-24

3
1. Radius of two spheres of same material are 1 & 4 m respectively and their temperature are 4 × 10
3
and 2 × 10 K respectively. Then ratio of emitted energy of spheres per sec. will be -

(1) 1 : 2 (2) 2 : 1 (3) 1 : 1 (4) 4 : 1

2. The rate of emission of radiation of a black body at 273°C is E, then the rate of emission of radiation

of this body at 0°C will be

E E E
(1) (2) (3) (4) 0
16 4 8

3. Two spheres P and Q of same colour having radii 8 cm and 2 cm are maintained at temperatures

127°C and 527°C respectively. The ratio of energy radiated by P and Q is -

(1) 0.054 (2) 0.0034 (3) 1 (4) 2

4. Two spheres of radii in the ratio 1 : 2 and densities in the ratio 2 1 and of same specific heat, are

heated to same temperature and left in the same surrounding. Their rate of falling temperature

will be in the ratio :

(1) 2 : 1 (2) 1 : 1 (3) 1 : 2 (4) 1 : 4

5. If temperature of ideal black body increased by 10%, then percentage increase in quantity of

radiation emitted from it's surface will be :-

(1) 10% (2) 40% (3) 46% (4) 100%

6. Cooling rate of a sphere of 600 K at external environment (200 K) is R. When the temperature of

sphere is reduced to 400 K then cooling rate of the sphere becomes :

3 16 9
(1) R (2) R (3) R (4) None
16 3 27

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7. The energy emitted per second by a black body at 27°C is 10 J. If temperature of the black body
is increased to 327°C, the energy emitted per second will be :-
(1) 20 J (2) 40 J (3) 80 J (4) 160 J

8. The original temperature of a black body is 727°C. Calculate temperature at which total radiant
energy from this black body becomes double:
(1) 971 K (2) 1190 K (3) 2001 k (4) 1458 K
9. Ratio of radius of curvature of cylindrical emitters of same material is 1 : 4 and their temperature
are in ratio 2 : 1. Then ratio of amount of heat emitted by them is - (For Cylinder length = radius)
(1) 2 : 1 (2) 1 : 1 (3) 4 : 1 (4) 1 : 4

10. Star S1 emits maximum radiation of wavelength 420 nm and the star S2 emits maximum radiation

of wavelength 560 nm, what is the ratio of the temperature of S1 and S2:
1/4 1/2
(1) 4/3 (2) (4/3) (3) 3/4 (4) (3/4)

11. The Wein's displacement law express relation between :-

(1) Wavelength corresponding to maximum energy and temperature.
(2) Radiation energy and wavelength
(3) Temperature and wavelength
(4) Colour of light and temperature

12. On increasing the temperature of a black body. wavelength for maximum emission.
(1) Shifts towards smaller wavelength
(2) Shifts towards greater wavelength
(3) Does not shift
(4) Depends on the shape of source.

13. Two spherical bodies A (radius 6 cm) and B (radius 18 cm) are at temperatures T1 and T2,

respectively. The maximum intensity in the emission spectrum of A is at 500 nm and in that of B
is at 1500 nm. Considering then to be black bodies, what will be the ratio of the rate of total energy
radiated by A to that of B?

14. Two spherical stars A and B emit blackbody radiation. The radius of A is 400 times that of B and

4 λ 
A emits 10 times the power emitted from B. The ratio  A  of their wavelengths λ A and λB at
 λb 
which the peaks occur in their respective radiation curves is.

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15. Two spheres of the same material have radii 1 m and 4 m and temperatures 4000 K to 2000 K

respectively. The ratio of the energy radiated per second by the first sphere to that by the second

is-

(1) 1 : 1 (2) 16 : 1 (3) 4 : 1 (4) 1 : 9

16. A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were

halved and the temperature doubled, the power radiated in watt would be :-

(1) 450 (2) 1000 (3) 1800 (4) 225

17. The power radiated by a black body is P and it radiates maximum energy at wavelength 20. If the

temperature of the black body is now changed so that it radiates maximum energy at wavelength

3
λ , the power radiated by it becomes nP. The value of n is :-
4 0

3 4 256 81
(1) (2) (3) (4)
4 3 81 256

18. Three stars A, B, C have surface temperatures TA, TB, TC respectively. Star A appears bluish, star B

appears reddish and star C yellowish. Hence,

(1) TA > TB > TC (2) TB > TC > TA (3) TC > TB > TA (4) TA > TC > TB

19. A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and

finally turns to white hot. The correct explanation for the above observation is possible by using:-

(1) Newton's Law of cooling (2) Stefan's Law

(3) Wein's displacement Law (4) Kirchoff's Law

20. A black body calorimeter filled with hot water cools from 60°C to 50°C in 4 min and 40°C to 30°C

in 8 min. The approximate temperature of surrounding is:

(1) 10°C (2) 15°C (3) 20°C (4) 25°C

21. Spheres P and Q are uniformly constructed from the same material which is a good conductor of

heat and the radius of Q is thrice the radius of P. The rate of fall of temperature of P is x times

that of Q when both are at the same surface temperature. The value of x is :

(1) 1/4 (2) 1/3 (3) 3 (4) 4

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22. A liquid in a beaker has temperature (t) at time t and θ0 is temperature of surroundings, then

according to Newton's law of cooling the correct graph between log. (θ – θ0) and t is :-

(1) (2)

(3) (4)

23. If a piece of metal is heated to temperature θ and then allowed to cool in a room which is at

temperature θ0 the graph between the temperature T of the metal and time t will be closed to:

(1) (2) (3) (4)

24. Two spheres of same radius R have their densities in the ratio 8 : 1 and the ratio of their specific

heats are 1 : 4. If by radiation their rates of fall of temperature are same, then find the ratio of

their rates of losing heat.

25. The maximum in the energy distribution spectrum of the sun is at 4753 Å and its temperature is

6050K. What will be the temperature of the star whose energy distribution shows a maximum at

9506 Å.

KTN01_P2185 4
SUBJECT: NEET-PHYSICS COURSE: MASTER PRO ELP No.-03 TOPIC: THERMAL EXPANSION
2023-24

1. A rectangular plate has a circular cavity as shown in the figure. If we increase its temperature then
which dimension will increase in following figure.
d

c
b

2. A small ring having small gap is shown in figure on heating what will happen to the size of gap.

3. Suppose there is a hole in a copper plate. On heating the plate, diameter of hole, would:
(1) always increase (2) always decrease
(3) always remain the same (4) none of these

4. What is the percentage change in length of 1 m iron rod if its temperature changes by 100°C. α for
iron is 2 × 10–5/°C.

5. The figure below shows four isotropic solids having positive coefficient of thermal expansion. A
student predicts that on heating the solid following things can happen. Mark true (T) or False (F)
for comments made by the student.

A
α B

(i) The angle α in figure (1) will not change.

(ii) The length of line in figure (2) will decrease.
(iii) The radius of inner hole will decrease.
(iv) The distance AB will increase.
(1) TFFT (2) FTTF (3) TTTT (4) FFTF

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6. Coefficient of linear expansion of brass and steel rods are α1 and α2. Lengths of brass and steel
rods are 1 and 2 respectively. If (2 – 1) is maintained same at all temperatures, which one of
the following relations holds good?
(1) α 1 2 =
α2  1 (2) α 122 =
α2 21 (3) α21  2 =
α22  1 (4) α 1 1 =α2  2

7. Two rods one of aluminium of length l1 having coefficient of linear expansion αa, and other steel
of length l2 having coefficient of linear expansion αs are joined end to end. The expansion in both
l1
the rods is same on variation of temperature. Then the value of is
l 1 + l2
αs αs αa + α s
(1) (2) (3) (4) None of these
αa + α s αa − α s αs

8. If two rods of length L and 2L having coefficients of linear expansion α and 2α respectively are
connected so that total length becomes 3L, determine the average coefficient of linear expansion
of the composite rod.

9. A thin copper wire of length L increase in length by 1% when heated from temperature T1 to T2.
What is the percentage change in area when a thin copper plate having dimensions 2L × L is heated
from T1 to T2?

10. )
An iron bar (Young's modulus = 1011 N / m2 , α =10−6 /° C 1m long and 10−3 m2 in area is heated from

0° C to 100° C without being allowed to bend or expand. Find the compressive force developed
inside the bar.
(1) 10000 N (2) 1000 N (3) 5000 N (4) 105 N

12. A rod of length 2m rests on smooth horizontal floor. If the rod is heated from 0° C to 20° C . Find
(
the longitudinal strain developed? α = 5 × 10−5 /° C )
(1) 10–3 (2) 2 × 10–3 (3) Zero (4) None

13. A glass vessel of volume 100 cm3 is filled with mercury and is heated from 25°C to 75°C. What
volume of mercury will overflow? Coefficient of linear expansion of glass = 1.8 × 10–6/°C and
coefficient of volume expansion of mercury is 1.8 × 10–4/°C.

14. There are two spheres of same radius and material at same temperature but one being solid while
the other hollow. Which sphere will expand more if they are heated to the same temperature?
Ans. As thermal expansion of isotropic solids is similar to true photographic enlargement, expansion
of a cavity is same as if it had been a solid body of the same material.

V V

i.e. ∆V= Vγ∆θ

As here V, γ and ∆θ are same for both solid and hollow spheres treated (cavity) ; so the expansion
of both will be equal.

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15. If a bimetallic strip is heated, it will
(A) bend towards the metal with lower thermal expansion coefficient.
(B) bend towards the metal with higher thermal expansion coefficient.
(C) twist itself into helix.
(D) have no bending.

Relation between α, β and γ

α β γ
(i) For isotropic solids: α : β : γ= 1 : 2 : 3 or = =
1 2 3
(ii) For non-isotropic solids β = α 1 + α2 and γ = α 1 + α2 + α 3 . Here α 1 , α2 and α 3 are coefficient
of linear expansion in X, Y and Z direction.

16. A copper rod of 88 cm and an aluminum rod of unknown length have their increase in length
independent of increase in temperature. The length of aluminum rod is :

(α Cu
= 1.7 × 10−5 K −1 and α Al = 2.2 × 10−5 K −1 )

(1) 6.8 cm (2) 113.9 cm (3) 88 cm (4) 68 cm

17. The value of coefficient of volume expansion of glycerin is 5 × 10–4K–1. The fractional change in the
density of glycerin for a rise of 40°C in its temperature, is :-
(1) 0.010 (2) 0.015 (3) 0.020 (4) 0.025

18. A pendulum clock consists of a light iron rod connected to a small, heavy bob. If it is designed to
keep correct time at 20°C, how fast or slow will it go in 24 hours at 40°C? Coefficient of linear
expansion of iron = 1.2 × 10–5/°C.

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SUBJECT: NEET-PHYSICS COURSE: MASTER PRO ELP No.-04 TOPIC: CALORIMETRY
2023-24

1. Find the quantity of heat required to convert 40 g of ice at –20°C into water at 20°C.

2. The amount of heat required in converting 1 g ice at – 10°C into steam at 100°C will be-
(1) 3028 J (2) 6056 J
(3) 721 J (4) 616 J

3. A bullet of mass 5 gm is moving with speed 400 m/s strike a target. Then calculate rise of
temperature of bullet. Assuming all the lose in kinetic energy is converted into heat energy of
bullet if its specific heat is 500 J/kg°C.

4. A body of mass 5 kg falls from a height of 30 metre. If its all mechanical energy is changed into
heat, then heat produced will be:-
(1) 350 cal (2) 150 cal (3) 60 cal (4) 6 cal

5. A bullet moving with velocity v collides against wall. consequently half of its kinetic energy is
converted into heat. If the whole heat is acquired by the bullet, the rise in temperature will be:-
(1) v 2 / 4S (2) 4v 2 / 2S (3) v 2 / 2S (4) v 2 / S

6. A block of ice with mass m falls into a lake. After impact, a mass of ice m/5 melts. Both the block
of ice and the lake have a temperature of 0°C. If L represents the heat of fusion, the minimum
distance the ice fell before striking the surface is
L 5L gL mL
(1) (2) (3) (4)
5g g 5m 5g

7. 1 kg ice at – 10°C is mixed with 1 kg water at 100°C. Then find equilibrium temperature and mixture
content.

8. 1 kg of ice at –10°C is mixed with 4.4 kg of water at 30°C. The final temperature of mixture is:
(specific heat
= of ice 2100 J / kg − k )
(1) 2.3°C (2) 4.4°C (3) 5.3°C (4) 8.7°C

9. If 10 g ice at 0°C is mixed with 10 g water at 20°C, the final temperature will be:-
(1) 50°C (2) 10°C (3) 0°C (4) 15°C

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10. Figure shows the temperature variation when heat is added continuously to a specimen of ice
(10g) at –40°C at constant rate.
(Specific heat of ice = 0.53 cal/g°C
= and Lice 80cal
= / g,Lwater 540cal / g )

Temp. (°C)
100

0
Q(cal)
–40
Q1 Q2 Q3 Q4
Column-I Column-II
(A) Value of Q1 (in cal) (P) 800
(B) Value of Q2 (in cal) (Q) 1000
(C) Value of Q3 (in cal) (R) 5400
(D) Value of Q4 (in cal) (S) 212
(T) 900
(1) A → S; B → P; C → Q; D → T (2) A → P; B → S; C → Q; D → R
(3) A → P; B → S; C → R; D → Q (4) A → S; B → P; C → Q; D → R

11. 1 kg ice at –10°C is mixed with 1 kg water at 100°C. Then find equilibrium temperature and mixture
content.

12. Steam at 100°C is added slowly to 1400 g of water at 16°C until the temperature of water is raised
to 80°C. The mass of steam required to do this is (LV = 540 cal/g):
(1) 160 g (2) 125 g (3) 250 g (4) 320 g

13. 50 g of ice at 0°C is mixed with 50 g of water at 100°C. The final temperature of mixture is:
(1) 0°C (2) Between 0°C to 20°C
(3) 20°C (4) Above 20°C

14. Liquid oxygen at 50 K is heated to 300 K at constant pressure of 1 atm. The rate of heating is
constant. Which one of the following graphs represents the variation of temperature with time?
Temp

Temp

(1) (2)

Time Time
Temp

Temp

(3) (4)

Time Time

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15. A slab of stone of area 0.36 m2 and thickness 0.1 m is exposed on the lower surface to steam at
100°C. A block of ice at 0°C rests on the upper surface of the slab. In one hour 4.8 kg of ice is
melted. The thermal conductivity of slab is : (Given latent heat of fusion of ice 3.36 × 105J kg–1 )
(1) 2.05 J/m/s/°C (2) 1.02 J/m/s/°C
(3) 1.24 J/m/s/°C (4) 1.29 J/m/s/°C

16. Steam at 100°C is passed into 20 g of water at 10°C. When water acquires a temperature of 80°C,
the mass of water present will be :
[Take specific heat of water = 1 cal g–1 °C–1 and latent heat of steam = 540 cal g–1]
(1) 24 g (2) 31.5 g (3) 42.5 g (4) 22.5 g

17. A piece of ice falls from a height h so that it melts completely. Only one-quarter of the heat
produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The
value of h is : [Latent heat of ice is 3.4 × 105 J/kg and g = 10 N/kg]
(1) 34 km (2) 544 km (3) 136 km (4) 68 km

18. Two identical bodies are made of a material for which the heat capacity increases with
temperature. One of these is at 100°C, while the other one is at 0°C. If the two bodies are brought
into contact, then, assuming no heat loss, the final common temperature is :-
(1) less than 50°C but greater than 0°C (2) 0°C
(3) 50°C (4) more than 50°C

19. The quantities of heat required to raise the temperature of two solid copper spheres of radii r1
and r2 (r1 = 1.5 r2) through 1 K are in the ratio:
5 27 9 3
(1) (2) (3) (4)
3 8 4 2

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