HARD

11th ICSE

IMPORTANT

Earn 100

An iron boiler is $1 cm$ thick and has a heating area of $2 m^{2}$ . The two surfaces of the boiler are at $234 ° C$ and $100 ° C$ respectively. If, the latent heat of steam is $536 kcal {kg}^{- 1}$ and thermal conductivity of iron is $1.6 \times 10^{- 2} kcal s^{- 1} m^{- 1} ° C^{- 1}$ , then how much water will be evaporated into steam per minute?

Important Questions on Thermal Conduction

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 11

Two rods of same metal and of same cross-section have lengths

0.5 m

and

0.8 m

. The temperature difference across the ends of the first rod is

40 ° C

. Find the temperature difference across the second rod, if the rate of heat conduction is equal in both the rods.

EASY

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 12

The temperature difference between the two ends of a bar

1.0 m

long is

50 ° C

and that for the other bar

1.25 m

long

75 ° C

. Both the bars have same area of cross-section. If the rates of conduction of heat in the two bars are the same, find the ratio of the coefficients of thermal conductivity of the materials of the two bars. If both the bars are of same metal, find the ratio of the rates of heat conduction in them.

EASY

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 13

Three thermometers

A

B

and

C

read respectively

36 ° C

32 ° C

and

27 ° C

A

lies between the body and vest of a man,

B

between vest and the shirt and

C

between the shirt and the coat. If the vest and the shirt are equally thick, calculate the ratio of their thermal conductivities.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 14

The ratio of the areas of cross-section of two rods of different materials is

1 : 2

and the ratio of the thermal conductivities of their materials is

4 : 3

. On keeping equal temperature-difference between the ends of these rods, the rate of conduction of heat are equal. Determine the ratio of the lengths of the rods.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 15

Two vessels of different materials are identical in size and shape. Both are filled with equal masses of boiled water and are placed on the same heater. If thermal conductivities of the metals of the vessels be

5 \times 10^{- 2}

and

3 \times 10^{- 2} k c a l s^{- 1} m^{- 1} ° C^{- 1}

respectively, then calculate the ratio of the timings taken by the water in the vessels to convert into steam.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 16

The plane surfaces of two sheets of different metals are kept in contact with each other. The thicknesses of sheets are

2.5 c m

and

3.0 c m

respectively and the ratio of their thermal conductivities in the same order is

5 : 6

. If the outer surfaces of the sheets are at constant temperatures of

100 ° C

and

10 ° C

respectively, calculate the temperature of interface.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 17

A composite wall of area

A

is made of equal thicknesses of lead and iron having thermal conductivities

K

and

2 K

respectively. The temperatures on the two sides of the composite wall are

100 ° C

and

0 ° C

with the lead layer on the hotter side. Calculate the steady-state temperature of the lead-iron interface.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 18

Two plates of equal areas are placed in contact with each other. Their thicknesses are

2.0

and

3.0 c m

respectively. The temperature of the external surface of the first plate is

- 25 ° C

and that of the external surface of the second plate is

25 ° C

. What will be the temperature of the contact-surface, if the plates are of the same material.

Important Questions on Thermal Conduction

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