MEDIUM

JEE Main/Advance

IMPORTANT

Earn 100

The figure shows a system of two concentric spheres of radii $r_{1}$ and $r_{2}$ and kept at temperatures $T_{1}$ and $T_{2}$ respectively. The radial rate of flow of heat in a substance between the two concentric sphere is proportional to

50% studentsanswered this correctly

Important Questions on Heat Transfer

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-1>Q 1

Three rods of the same dimensions have thermal conductivities $3 k, 2 k$ and $k$ . They are arranged as shown with their ends at $100 ° C, 50 ° C$ and $0 ° C$ . The temperature of their junction is:

Question Image

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-1>Q 7

The area of cross-section of rod is given by

A = A_{0} (1 + α x)

where

A_{0} & α

are constant and

x

is the distance from one end. If the thermal conductivity of the material is

K

, what is the thermal resistance of the rod if its length is

l_{0}

MEDIUM

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-2>Q 1

Radiation from a black body at the thermodynamic temperature

T_{1}

is measured by a small detector at distance

d_{1}

from it. When the temperature is increased to

T_{2}

and the distance to

d_{2}

, the power received by the detector is unchanged. What is the ratio

d_{2} / d_{1}

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-2>Q 2

A point source of heat of power

P

is placed at the center of a spherical shell of mean radius

R

. The material of the shell has thermal conductivity

k

. If the temperature difference between the outer and the inner surface of the shell is not to exceed

T

, then the thickness of the shell should not be less than :-

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-2>Q 3

A black body emits radiation at the rate

P

when its temperature is

T

. At this temperature the wavelength at which the radiation has a maximum intensity is

λ_{0}

. If at another temperature

T^{'}

the power radiated is

P^{'}

and wavelength at maximum intensity is

λ_{0} / 2

then

EASY

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-3>Q 17

Calculate

θ_{1}

and

θ_{2}

in shown situation.

Question Image

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-3>Q 18

An electric heater is used in a room of total wall area

137 m^{2}

to maintain a temperature of

+ 20 ° C

inside it, when the outside temperature is

- 10 ° C

. The walls have three different layers of materials. The innermost layer is of wood of thickness

2.5 c m

, the middle layer is of cement of thickness

1.0 c m

and the outermost layer is of brick of thickness

25.0 c m

. The power of electric heater (in

W

) is

x \times 10^{3} W

. Write the value of

x

to the nearest integer. Assume that there is no heat loss through the floor and the ceiling. The thermal conductivities of wood, cement and brick are

0.125, 1.5

and

1.0 W m^{- 1} ° C^{- 1}

, respectively.

HARD

JEE Main/Advance

IMPORTANT

Beta Question Bank for Engineering: Physics>Chapter 16 - Heat Transfer>Exercise-4>Q 2

A double-pane window used for insulating a room thermally from outside consists of two glass sheets each of area

1 m^{2}

and thickness

0.01 m

separated by a

0.05 m

thick stagnant air space. In the steady state, the room glass interface and the glass-outdoor interface are at constant temperature of

27^{\circ} C

and

0^{\circ} C

respectively. Calculate the rate of heat flow through the window pane. Also find the temperatures of other interfaces. Given thermal conductivities of glass and air as

0.8

and

0.08 W m^{- 1} K^{- 1}

respectively.

The figure shows a system of two concentric spheres of radii r1 and r2 and kept at temperatures T1 and T2 respectively. The radial rate of flow of heat in a substance between the two concentric sphere is proportional to

Important Questions on Heat Transfer

Learn and Prepare for any exam you want !

The figure shows a system of two concentric spheres of radii $r_{1}$ and $r_{2}$ and kept at temperatures $T_{1}$ and $T_{2}$ respectively. The radial rate of flow of heat in a substance between the two concentric sphere is proportional to