A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 8

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11th West Bengal Board

IMPORTANT

Earn 100

State and explain Stefan-Boltzmann Law. Using the law deduce Newton's law of cooling which states that if the temperature difference between a hot body and its surroundings be small, the rate of cooling of the body is proportional to the excess temperature of the body over the surroundings.

Important Questions on Heat Transfer

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11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 9

Two metallic plates of equal cross-sectional area and thickness

d_{1}

and

d_{2}

and thermal conductivities

k_{1}

and

k_{2}

are placed in contact. Prove that their equivalent thermal conductivity is given by

k = \frac{d_{1} + d_{2}}{\frac{d_{1}}{k_{1}} + \frac{d_{2}}{k_{2}}}

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11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 10

Three slabs are of thickness

d_{1}, d_{2}

and

d_{3}

. They are of same length and breadth. The thermal conductivities of the material of the slabs are

k_{1}

and

k_{2}

respectively. They are piled one over the other in the order

1, 2, 3

. Show that the combination behaves at the steady state as a single slab of thermal conductivity

k,

given by

\frac{d_{1} + d_{2} + d_{3}}{k} = \frac{d_{1}}{k_{1}} + \frac{d_{2}}{k_{2}} + \frac{d_{3}}{k_{3}}

(neglect radiation).

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11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 11

State the main properties of radiant heat.

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11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 12

What is a perfectly black body? Explain Ferry's black body.

EASY

11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 13

State an explain Kirchoff's law for black body radiation.

EASY

11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 14

State and explain Newton's law of cooling.

EASY

11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 15

What is Faery's black body?

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11th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 16

What is Provosts theory of exchange?