MEDIUM

11th ICSE

IMPORTANT

Earn 100

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.

Important Questions on Thermal Conduction

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.

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 cm

and

3.0 cm

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, have thermal conductivities in the ratio

2 : 3

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 19

An ice box made of

1.75 cm

thick wood has on the inner side a

2.0 cm

thick layer of cork. If, the temperature of the inner surface of the cork is

0 ° C

and that of the outer surface of wood is

12 ° C

, then find the temperature of the interface. Thermal conductivity of wood is

5

times that of cork.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 20

A square sheet of cork of side

20 cm

and thickness

3.0 mm

is placed in contact of a square glass sheet of side

20 cm

and thickness

5.0 mm

. The outer faces of this composite sheet are maintained at

100 ° C

and

20 ° C

, the cork face being at higher temperature. Find the temperature of the cork-glass interface. The thermal conductivities of cork and glass are

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

and

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

respectively.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 21

A bar of copper of length

0.75 m

and a bar of stainless steel of length

1.25 m

are joined end to end, each having a cross-sectional area of

101 m^{2}

. The free ends of the copper and the steel bars are maintained at

100 ° C

and

0 ° C

respectively. Find the temperature of the copper-steel junction.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 24 - Thermal Conduction>NUMERICALS>Q 21

A bar of copper of length

0.75 m

and a bar of stainless steel of length

1.25 m

are joined end to end, each having a cross-sectional area of

101 m^{2}

. The free ends of the copper and the steel bars are maintained at

100 ° C

and

0 ° C

respectively. Calculate the rate of heat transmission across the junction. Thermal conductivities of copper and steel are

400

and

14 J m^{- 1} s^{- 1} K^{- 1}

respectively.

Important Questions on Thermal Conduction

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