Radiation

Q.

What are the properties of thermal radiations?

Q.

Heat loss from surface by radiation can be reduced by :

1. blackening the surface

2. keeping the surface in vacuum

3. keeping it in dark

4. polishing the surface

Q.

Black surfaces are better ______________________ of heat than polished surfaces.

Q. Match the following based on their predominant modes of heat transfer.

1. Liquids
2. Solids
3. Vacuum

Q. Heat tranfer by radiation can only take place through vacuum.

1. True
2. False

Q. Which of the following pairs have same dimensions.
a) Torque and work
b) Angular momentum and work
c) Energy and Youngs modulus
d) Light year and wavelength

1. a and b are correct
2. b and c are correct
3. c and d are correct
4. d and a are correct

Q. Heat from the Sun reaches the Earth by:

1. Vaporization
2. Convection
3. Conduction
4. Radiation

Q. Heat radiations travel with a speed _______ the speed of light.

1. equal to
2. less than
3. more than
4. Insufficient information

Q.

Is the Earths atmosphere mainly heated by conduction , convection or radiation?

Q. Radiation of heat from a body can never be stopped.

1. True
2. False
3. Either
4. Neither

Q. heat from a burning candle travels by convection or radiation

Q. Consider the radiations emitted by the human body. Which of the following statements is true?

1. radiations lie in ultraviolet region
2. radiations are emitted only during the day
3. radiations are emitted during summer and absorbed during winter
4. radiations lie in infrared region