Thermal Properties of Matter

Which of the following is closest to an ideal black body?

1. lamp black
2. cavity maintained at constant temperature
3. platinum black
4. a lump of charcoal heated to high temperature.

The Wien's displacement law expresses 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.

A cylindrical rod has temperatures T1 and T2 at its ends. The rate of flow of heat is Q1 cal/s. If all the linear dimensions are doubled keeping the temperatures constant, then the rate of flow of heat Q2 will be

1. 4Q1
2. 2Q1
3. Q14
4. Q12

Gravitational force is required for

1. stirring of liquid
2. convection
3. conduction
4. radiation

A black body emits maximum energy at wavelength m at 2000 K. Its corresponding wavelength at 3000 K will be

1. 32 m
2. 23 m
3. 1681 m
4. 8116 m