Physics questions
20027 published questions with worked solutions.
- Which of the following is the example of ideal black body
- Reflectivity of a perfectly black body is
- Three bodies A, B and C have equal area which are painted red, yellow and black respectively If they are at same temperature then
- Unit of emissive power is
- A body of surface area 5 cm² and temperature 727° C, emits 300 Joules of energy per minute Its emissivity will be
- The temperature of a tungsten bulb is 3000 K. the area of its surface is 0.25 cm² and emissivity is 0.35, then the power of bulb...
- A body of surface area 15 10^ -3 m² emits 0.3 kcal in 40 second at a temperature 70°C, the emissive power of the surface at that...
- Emissive power of cube is 1000 J/m²s and it radiates heat at the rate 60 watt at that temperature. The length of each side of...
- The emissive power of a sphere of area 0.07 m² is 0.5 k cal/ m²s. The amount of heat radiated by the spherical surface, in 20...
- A sphere of radius 50 cm is maintained at a constant temperature, radiates energy at the rate of 0.5 kcal/s. Then the emissive...
- A metal cube with each side 3 cm long emits 0.27 kcal in 100s. Then its emissive power is
- The emissive power of a surface depends upon:
- Emissivity of perfectly black body is
- The amount of heat energy radiated per seconds by a surface depends up on :
- The emissivity (e) of any body at a temperature is:
- E is emissive power and 'a' is the coefficient of absorption of a body at a certain temperature. If E_b is the emissive power of...
- Which of the following is best close to an ideal black body?
- A good absorber is a :
- Which of the following is more close to a black body?
- Highly polished surface are ________ of heat radiations: