Q. Which one is true for opaque body?

View solution

Q. Energy strikes a vertical hemispherical plate with an intensity of 640 W/m². The absorptivity is thrice the transmissivity and twice the reflectivity. Determine the rate of transmission

View solution

Q. The absorptivity of a surface depends upon

(i) Direction of reflected radiation
(ii) Temperature of the surface
(iii) Composition

Identify the correct statements

View solution

Q. What is the absorptivity of gray body?

View solution

Q. A body that reflects all the incident thermal radiations is called a

View solution

Q. Energy strikes a vertical hemispherical plate with an intensity of 640 W/m². The absorptivity is thrice the transmissivity and twice the reflectivity. Determine the rate of absorption

View solution

Q. Let 220 W/m² of radiant energy is absorbed by a convex surface, 90 W/m² is reflected and 40 W/m² is transmitted through it. What is the value of absorptivity?

View solution

Q. For a grey surface

View solution

Q. Which quantity can be neglected for gases?

View solution

Q. Absorptivity of a body is equal to its emissivity

View solution

Q. Electromagnetic waves strikes a hot body maintained at 900 degree Celsius which has a reflectivity of 0.66 and a transmissivity of 0.022. Let the absorbed flux be 60 W/m². Determine the rate of incident flux

View solution

Q. Radiation heat transfer is characterized by

View solution

Q. Which is true regarding radiation?

View solution

Q. Radiation exchange occurs in

View solution

Q. Energy released by a radiating surface is not continuous but is in the form of successive and separate packets of energy called

View solution

Q. The electromagnetic waves are emitted as a result of

(i) Vibrational movement
(ii) Rotational movement
(iii)Atomic or sub-atomic particles comprising the matter

Identify the correct statement

View solution

Q. Thermal radiations occur in the portion of electromagnetic spectrum between the wavelengths

View solution

Q. A perfectly black body

View solution

Q. What is the wavelength band for cosmic rays?

View solution

Q. For a prescribed wavelength a black body radiates how much energy at the temperature of body?

View solution