A system of weight 7 K g is heated from its initial temperature of 30 ∘ C to its final temperature of 60 ∘ C . Find out the total heat obtained by the system. Note that the specific heat of the system is 0 . 45 k J p e r K g K .

Initial temperature of the system, T i = 30 ∘ C , Final temperature of the system, T f = 60 ∘ C , Mass of the system, m = 7 k g , The total heat gained by the system can be computed by using the formula for heat transfer as given: Q = m × c × ∆ T Q = m × c × T f - T i s o , Q = 7 × 0 . 45 × 60 - 30 Q = 7 × 0 . 45 × 30 t h e r e f o r e , Q = 94 . 5 T h e r e f o r e , t o t a l h e a t o b t a i n e d i s 94 . 5 J o u l e H e n c e , i t i s t h e r e q u i r e d a n s w e r

E M B I B E

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 17

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IMPORTANT

Earn 100

"Good reflectors are poor emitters of thermal radiation." explain.

Important Questions on Heat Transfer

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IMPORTANT

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

What are emissive power and absorptive power.

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IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 19

"Good absorbers are good emitters, while poor absorbers are poor emitters" justify the statement from Kirchoff's law.

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IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 20

A system of weight

7 K g

is heated from its initial temperature of

30^{\circ} C

to its final temperature of

60^{\circ} C

. Find out the total heat obtained by the system. Note that the specific heat of the system is

0.45 k J p e r K g K

.

EASY

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IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 21

Obtain Newtons law of cooling from Stefan's law.

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A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 22

What is the black body? Draw the curves showing the energy distribution among black body radiations at different temperatures. Hence, define Wein displacement law. Give one application of Wein displacement law.

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A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 23

Why the radiation from a perfects black body is said to have a universal character?

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A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 24

State Wien's displacement law. Explain what changes we observe if we continue a iron ball heating and raise its temperature to higher and higher values.

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IMPORTANT

A Text Book of PHYSICS PART I : CLASS 11>Chapter 18 - Heat Transfer>EXERCISE>Q 25

Define a perfectly black body. Explain how the nature of radiation from a perfectly black body changes as its temperature increases.