The emissive power of a black body at `T=300K` is `100Watt//m^(2)` consider a body B of area `A=10m^(2)` coefficient of reflectivity `r=0.3` and coefficient of transmission `t=0.5` its temperature is 300 K. then which of the followin is correct:A. The emissive power of `B` is `20W//m^(2)`B. The emissive power of `B` is `200W//m^(2)`C. The power emitted by `B` is `200"Watt"`D. The emissivity of `B` is =` 0.2`

The emissive power of a black body at `T=300K` is `100Watt//m^(2)` con

1.	The emissive power of a black body at `T=300K` is `100Watt//m^(2)` consider a body B of area `A=10m^(2)` coefficient of reflectivity `r=0.3` and coefficient of transmission `t=0.5` its temperature is 300 K. then which of the followin is correct:A. The emissive power of `B` is `20W//m^(2)`B. The emissive power of `B` is `200W//m^(2)`C. The power emitted by `B` is `200"Watt"`D. The emissivity of `B` is =` 0.2`
Answer» Correct Answer - B For body `AP = sigmaAT^(4)` `(P)/(A) = 100 = sigma xx 300^(4)` For body `B` `(P)/(A) = (sigmaT^(4)) in = (1-0.5-0.3) xx [sigmaxx300^(4)]` ` = 0.2 xx 100 = 20W//m^(2)`

Discussion

No Comment Found

Related InterviewSolutions

A symmetric doule convex lens is cut in two equal parts by a plane perpendiculr to the pricipal axis. If the power of the original lens was 4D, the power of a cut lens will beA. 2DB. 3DC. 4DD. 5D
Three perfect gases at absolute temperature `T_(1), T_(2)` and `T_(3)` are mixed. The masses f molecules are `m_(1), m_(2)` and `m_(3)` and the number of molecules are `n_(1), n_(2)` and `n_(3)` respectively. Assuming no loss of energy, the final temperature of the mixture isA. `(n_(1)T_(1)^(2) + n_(2)T_(2)^(2) + n_(3)T_(3)^(2))/(n_(1)T_(1) + n_(2)T_(2) + n_(3)T_(3))`B. `(n_(1)^(2)T_(1)^(2) + n_(2)^(2)T_(2)^(2) + n_(3)^(2)T_(3)^(2))/(n_(1)T_(1) + n_(2)T_(2) + n_(3)T_(3))`C. `(T_(1) + T_(2) + T_(3))/(3)`D. `(n_(1)T_(1) + n_(2)T_(2) + n_(3)T_(3))/(n_(1) + n_(2) + n_(3))`
The critical angle for water is `48.2^@`. Find is refractive index.
Find the size of the image formed in the situation shown in figure.
The angle of minimum, deviation from a prism is `37^@`. If the angle of prism is `53^@`, find the refrence index of the material of the prism.
A prism of refractive index `1.53` is placed in water of refractive index `1.33`. If the angle of prism is `60^@`, calculate the angle of minimum deviation in water.
Light passes symmetrically through a `60^(@)` prism of refractive index 1.54. After emergence out from the prism the light ray is incident on a plane mirror fixed to the base of the prism extending beyond it. Find the total deviation of the light ray after reflection from the mirror.
A vertical beam of light of cross sectional radius `(R)/(2)` is incident symmetrically on the curved surface of a glass hemisphere of refractive index `mu = (3)/(2)`. Radius of the hemisphere is R and its base is on a horizontal table. Find the radius of luminous spot formed on the table. `sin 20^(@) = (1)/(3)` and `sin 80^(@) = 0.98`
An obsever looks at a distant tree of height 10m with a telescope of magnifying power of 20. to the observer the tree appears:A. 20 times nearerB. 10 times tallerC. 10 times nearerD. 20 times taller
A large transparent cube (refractive index = 1.5) has a small air bubble inside it. When a coin (diameter 2 cm) is placed symmetrically above the bubble on the top surface of the cube, the bubble cannot be seen by looking down into the cube at any angle. However, when a smaller coin (diameter 1.5 cm) is placed directly over it, the bubble can be seen by looking down into the cube. What is the range of the possible depths d of the air bubble beneath the top surface ?

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment