A black body at temperature 300K radiates heat at the rate E. If its temperature is increased by 600K, the rate of radiation will increase to -

1.  16E

2.  64E

3.  81E

4.  256E

Subtopic:  Radiation |
From NCERT
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A body cools down from \(80^{\circ}\mathrm{C}\) to \(70^{\circ}\mathrm{C}\) in 5 minutes. The temperature of the same body will fall from \(70^{\circ}\mathrm{C}\) to \(60^{\circ}\mathrm{C}\) in:

1. less than 5 minutes.
2. equal to 5 minutes.
3. more than 5 minutes.
4. can't say anything as the temperature of the surroundings is not known.

Subtopic:  Newton's Law of Cooling |
 62%
From NCERT
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If λm is the wavelength, corresponding to which the radiant intensity of a block is at its maximum and its absolute temperature is T, then which of the following graph correctly represents the variation of T?

1. 2.
3. 4.

Subtopic:  Wien's Displacement Law |
 74%
From NCERT
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Heat capacity is equal to the product of:

1.  mass and gas constant

2.  mass and specific heat

3.  latent heat and volume of water

4.  mass and Avogadro number

 

Subtopic:  Calorimetry |
 90%
From NCERT
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When a block of iron floats in Hg at 0°C, a fraction K1 of its volumen= is submerged, while at temperature of 60°C a fraction K2 is seen to be submersed. If the coefficient of volume expansion of iron is γFe and that of mercury is γHg, then the ratio K1K2 can be expressed as:

1. 1+60γFe1+60γHg

2. 1-60γFe1+60γHg

3. 1+60γFe1-60γHg

4. 1+60γHe1-60γFe

Subtopic:  Thermal Expansion |
 51%
From NCERT
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Hot water cools from 60°C to 50°C in first 10 minutes and from 50°C to 42°C in next 10 minutes. The temperature of surrounding is :

1.  5° C 

2.  10° C 

3.  15° C  

4.  20°C

 

Subtopic:  Newton's Law of Cooling |
 77%
From NCERT
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A pendulum clock runs faster by 5 seconds per day at \(20^{\circ}\mathrm {C}\) and goes slow by 10 second per day at \(35^{\circ}\mathrm {C}\). It shows the correct time at a temperature of:
1. \(27.5^{\circ}\mathrm {C}\)
2. \(25^{\circ}\mathrm {C}\)
3. \(30^{\circ}\mathrm {C}\)
4. \(33^{\circ}\mathrm {C}\)
 

Subtopic:  Thermal Expansion |
 66%
From NCERT
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A constrained steel rod of length l, area of cross-section A, Young's modulus Y and coefficient of linear expansion α is heated through \(t^{\circ}\mathrm{C}\). The work that can be performed by the rod when heated is:
1. (YAαt)(lαt)
2. 12(YAαt)(lαt)
3. 12(YAαt)12(lαt)
4. 2(YAαt)(lαt)

Subtopic:  Thermal Stress |
 63%
From NCERT
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The temperature of a body on Kelvin scale is found to be X K. When it is measured by a Fahrenheit thermometer, it is found to be X0F. Then X is

(1) 301.25

(2) 574.25

(3) 313

(4) 40

Subtopic:  Temperature and Heat |
 66%
From NCERT
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A temperature of \(100^{\circ}\mathrm {F}\) (Fahrenheit scale) is equal to T K (Kelvin scale). The value of T is:
1.  310.9
2.  37.8
3.  100
4.  122.4

Subtopic:  Temperature and Heat |
 74%
From NCERT
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