# The value of the coefficient of volume expansion of glycerine is $$5\times10^{-4} \mathrm{~K^{-1}}$$. The fractional change in the density of glycerine for a rise of $$40^\circ \text{C}$$ in its temperature is: 1. $$0.015$$ 2. $$0.020$$ 3. $$0.025$$ 4. $$0.010$$

Subtopic:  Thermal Expansion |
81%
From NCERT
NEET - 2015
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On observing light from three different stars $$P$$, $$Q$$, and $$R$$, it was found that the intensity of the violet colour is maximum in the spectrum of $$P$$, the intensity of the green colour is maximum in the spectrum of $$R$$ and the intensity of the red colour is maximum in the spectrum of $$Q$$. If $$T_P$$$$T_Q$$, and $$T_R$$ are the respective absolute temperatures of $$P$$, $$Q$$, and $$R$$, then it can be concluded from the above observations that:
1. $$T_P>T_Q>T_R$$
2. $$T_P>T_R>T_Q$$
3. $$T_P<T_R<T_Q$$
4. $$T_P<T_Q<T_R$$

Subtopic:  Wien's Displacement Law |
65%
From NCERT
NEET - 2015
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The two ends of a metal rod are maintained at temperatures $$100~^\circ\text{C}$$ and $$110~^\circ\text{C}.$$ The rate of heat flow in the rod is found to be $$4.0$$ J/s. If the ends are maintained at temperatures $$200~^\circ \text{C}$$ and $$210 ~^\circ \text{C},$$ the rate of heat flow will be:
1. $$44.0$$ J/s
2. $$16.8$$ J/s
3. $$8.0$$ J/s
4. $$4.0$$ J/s

Subtopic:  Conduction |
83%
From NCERT
NEET - 2015
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Steam at $$100~^{\circ}\mathrm{C}$$ is passed into $$20~\text{g}$$ of water at $$10~^{\circ}\mathrm{C}$$. When water acquires a temperature of $$80~^{\circ}\mathrm{C}$$, the mass of water present will be:
[Take specific heat of water $$= 1~\text{cal g}^{-1}~^\circ\mathrm{C}^{-1}$$ and latent heat of steam $$= 540~\text{cal g}^{-1}$$]
1. $$24~\text{g}$$
2. $$31.5~\text{g}$$
3. $$42.5~\text{g}$$
4. $$22.5~\text{g}$$

Subtopic:  Calorimetry |
69%
From NCERT
AIPMT - 2014
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A certain quantity of water cools from $$70~^{\circ}\text{C}$$ to $$60~^{\circ}\text{C}$$ in the first $$5$$ minutes and to $$54~^{\circ}\text{C}$$ in the next $$5$$ minutes. The temperature of the surroundings is:
1. $$45~^{\circ}\text{C}$$
2. $$20~^{\circ}\text{C}$$
3. $$42~^{\circ}\text{C}$$
4. $$10~^{\circ}\text{C}$$

Subtopic:  Newton's Law of Cooling |
76%
From NCERT
AIPMT - 2014
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A piece of iron is heated in a flame. It first becomes dull red, then becomes reddish yellow and finally turns to white-hot. The correct explanation for the above observation is possible by using:
1. Wien’s displacement Law
2. Kirchoff’s Law
3. Newton’s Law of cooling
4. Stefan’s Law
Subtopic:  Wien's Displacement Law |
82%
From NCERT
AIPMT - 2013
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If the radius of a star is $$R$$ and it acts as a black body, what would be the temperature of the star at which the rate of energy production is $$Q$$?
1. $$\frac{Q}{4\pi R^2\sigma}$$
2. $$\left(\frac{Q}{4\pi R^2\sigma}\right )^{\frac{-1}{2}}$$
3. $$\left(\frac{4\pi R^2 Q}{\sigma}\right )^{\frac{1}{4}}$$
4. $$\left(\frac{Q}{4\pi R^2 \sigma}\right)^{\frac{1}{4}}$$

Subtopic:  Stefan-Boltzmann Law |
83%
From NCERT
AIPMT - 2012
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Liquid oxygen at $$50$$ K is heated up to $$300$$ K at a constant pressure of $$1$$ atm. The rate of heating is constant. Which one of the following graphs represents the variation of temperature with time?

 1 2 3 4
Subtopic:  Calorimetry |
80%
From NCERT
AIPMT - 2012
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A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat Q in time t. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod when placed in thermal contact with the two reservoirs at the same time?

1. Q /4

2. Q/16

3. 2Q

4. Q/2

Subtopic:  Conduction |
60%
From NCERT
AIPMT - 2010
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The total radiant energy per unit area, normal to the direction of incidence, received at a distance $$R$$ from the centre of a star of radius $$r,$$ whose outer surface radiates as a black body at a temperature $$T$$ K is given by: (Where $$\sigma$$ is Stefan’s constant):
1. $$\frac{\sigma r^{2}T^{4}}{R^{2}}$$

2. $$\frac{\sigma r^{2}T^{4}}{4 \pi R^{2}}$$

3. $$\frac{\sigma r^{2}T^{4}}{R^{4}}$$

4. $$\frac{4\pi\sigma r^{2}T^{4}}{R^{2}}$$

Subtopic:  Stefan-Boltzmann Law |
63%
From NCERT
AIPMT - 2010
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