# Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at $$100~^{\circ}\mathrm{C}$$, while the other one is at $$0~^{\circ}\mathrm{C}.$$ If the two bodies are brought into contact, then assuming no heat loss, the final common temperature is: 1. $$50~^{\circ}\mathrm{C}$$ 2.  more than $$50~^{\circ}\mathrm{C}$$ 3.  less than $$50~^{\circ}\mathrm{C}$$ but greater than $$0~^{\circ}\mathrm{C}$$ 4. $$0~^{\circ}\mathrm{C}$$

Subtopic:  Calorimetry |
64%
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NEET - 2016
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A body cools from a temperature of $$3T$$ to $$2T$$ in $$10$$ minutes. The room temperature is $$T$$. Assuming that Newton's law of cooling is applicable, the temperature of the body at the end of the next $$10$$ minutes will be:

 1 $$\frac{7}{4}T$$ 2 $$\frac{3}{2}T$$ 3 $$\frac{4}{3}T$$ 4 $$T$$

Subtopic:  Newton's Law of Cooling |
72%
From NCERT
NEET - 2016
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The coefficient of linear expansion of brass and steel rods are $$\alpha_1$$ and $$\alpha_2$$. Lengths of brass and steel rods are $$L_1$$ and $$L_2$$ respectively. If $$(L_2-L_1)$$ remains the same at all temperatures, which one of the following relations holds good?
1. $$\alpha_1L_2^2=\alpha_2L_1^2$$
2. $$\alpha_1^2L_2=\alpha_2^2L_1$$
3. $$\alpha_1L_1=\alpha_2L_2$$
4. $$\alpha_1L_2=\alpha_2L_1$$

Subtopic:  Thermal Expansion |
88%
From NCERT
NEET - 2016
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A black body is at a temperature of $$5760~\mathrm{K}$$. The energy of radiation emitted by the body at wavelength $$250~\mathrm{nm}$$ is $$U_1$$, at wavelength $$500~\mathrm{nm}$$ is $$U_2$$ and that at $$1000~\mathrm{nm}$$ is $$U_3$$. Wien’s constant, $$\mathrm{b}=2.88 \times 10^6 \mathrm{~nm}-\mathrm{K}$$. Which of the following is correct?
1. $$\mathrm{U}_3 =0$$
2. $$\mathrm{U}_1 >\mathrm{U}_2$$
3. $$\mathrm{U}_2 >\mathrm{U}_1$$
4. $$\mathrm{U}_1 =0$$
Subtopic:  Wien's Displacement Law |
64%
From NCERT
NEET - 2016
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A piece of ice falls from a height $$h$$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice. The value of $$h$$ is:
[Latent heat of ice is $$3.4 \times 10^5~\text{J/kg}$$ and $$g=10~\text{N/kg}$$]
1. $$544~\text{km}$$
2. $$136~\text{km}$$
3. $$68~\text{km}$$
4. $$34~\text{km}$$
Subtopic:  Calorimetry |
81%
From NCERT
NEET - 2016
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The power radiated by a black body is $$P$$ and it radiates maximum energy at wavelength ${}_{}$$$\lambda_0$$. Temperature of the black body is now changed so that it radiates maximum energy at the wavelength $$\frac{3}{4}\lambda_0$$. The power radiated by it now becomes $$nP$$. The value of $$n$$ is:
1. $$\frac{3}{4}$$
2. $$\frac{4}{3}$$
3. $$\frac{256}{81}$$
4. $$\frac{81}{256}$$

Subtopic:  Wien's Displacement Law |
65%
From NCERT
NEET - 2018
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Two rods $$A$$ and $$B$$ of different materials are welded together as shown in the figure. Their thermal conductivities are $$K_1$$ and $$K_2.$$ The thermal conductivity of the composite rod will be:

 1 $$\frac{3(K_1+K_2)}{2}$$ 2 $$K_1+K_2$$ 3 $$2(K_1+K_2)$$ 4 $$\frac{(K_1+K_2)}{2}$$
Subtopic:  Conduction |
72%
From NCERT
NEET - 2017
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A piece of ice falls from a height $$h$$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice, and all energy of ice gets converted into heat during its fall. The value of $$h$$ is: (Latent heat of ice is $$3.4\times10^5$$ J/kg and $$g=10$$ N/kg)

 1 $$544$$ km 2 $$136$$ km 3 $$68$$  km 4 $$34$$ km
Subtopic:  Calorimetry |
75%
From NCERT
NEET - 2016
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A spherical black body with a radius of 12 cm radiates 450-watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watts would be:

 1 225 2 450 3 1000 4 1800
Subtopic:  Stefan-Boltzmann Law |
74%
From NCERT
NEET - 2017
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