# Gravitational force is required for: 1. stirring of liquid 2. convection 3. conduction 4. radiation

Subtopic:  Convection |
76%
From NCERT
AIPMT - 2000
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The temperature of inversion of a thermocouple is 620ºC and the neutral temperature is 300ºC. What is the temperature of the cold junction:

1. 40ºC

2. 20ºC

3. 320ºC

4. –20ºC

Subtopic:  Conduction |
AIPMT - 2005
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Which of the following circular rods, (given radius $$r$$ and length $$l$$) each made of the same material and whose ends are maintained at the same temperature will conduct the most heat:

 1 $$r=2r_0;~l=2l_0$$ 2 $$r=2r_0;~l=l_0$$ 3 $$r=r_0;~l=2l_0$$ 4 $$r=r_0;~l=l_0$$
Subtopic:  Conduction |
85%
From NCERT
AIPMT - 2005
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Radiation energy corresponding to the temperature T of the sun is E. If its temperature is doubled, then its radiation energy will be:
1. 32 E
2. 16 E
3. 8 E
4. 4 E

Subtopic:  Stefan-Boltzmann Law |
90%
From NCERT
AIPMT - 1998
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A sphere maintained at a temperature of 600 K, has a cooling rate R in an external environment of 200 K temperature. If its temperature falls to 400 K, then its cooling rate will be:

1. $\frac{3}{16}R$

2. $\frac{16}{3}R$

3. $\frac{9}{27}R$

4. None

Subtopic:  Stefan-Boltzmann Law |
From NCERT
AIPMT - 1999
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If λm denotes the wavelength at which the radioactive emission from a black body at a temperature T K is maximum, then:

1. λm is independent of T

2. λm ∝ T

3. λm ∝ T–1

4. λm ∝ T– 4

Subtopic:  Wien's Displacement Law |
85%
From NCERT
AIPMT - 2004
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Two conducting slabs of heat conductivity $$K_{1} ~\text{and}~K_{2}$$ are joined as shown in figure. If the temperature at the ends of the slabs are $$\theta_{1}~\text{and}~\theta_{2} \ (\theta_{1} > \theta_{2} ),$$ then the final temperature $$\left(\theta\right)_{m}$$ of the junction will be:

 1 $$\frac{K_{1} \theta_{1} + K_{2} \theta_{2}}{K_{1} + K_{2}}$$ 2 $$\frac{K_{1} \theta_{2} + K_{2} \theta_{1}}{K_{1} + K_{2}}$$ 3 $$\frac{K_{1} \theta_{2} + K_{2} \theta_{1}}{K_{1} - K_{2}}$$ 4 None
Subtopic:  Conduction |
83%
From NCERT
AIPMT - 1999
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Wien's displacement law expresses the relation between:

 1 Wavelength corresponding to maximum energy and temperature 2 Radiation energy and wavelength 3 Temperature and wavelength 4 Colour of light and temperature
Subtopic:  Wien's Displacement Law |
67%
From NCERT
AIPMT - 2002
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Which of the following is closest to an ideal black body?

 1 Black lamp 2 Cavity maintained at a constant temperature 3 Platinum black 4 A lump of charcoal heated to high temperature
54%
From NCERT
AIPMT - 2002
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For a black body at a temperature of 727ºC, its radiating power is 60 watts and the temperature of the surroundings is 227ºC. If the temperature of the black body is changed to 1227ºC then its radiating power will be:

1. 304 W

2. 320 W

3. 240 W

4. 120 W

Subtopic:  Stefan-Boltzmann Law |
62%
From NCERT
AIPMT - 2002
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