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Which of the following statement is wrong? (a) Rough surfaces are better radiators tan smooth surfaces (b) Highly polished mirror surfaces are very good radiators (c) Black surfaces are better absorbers then white ones (d) Black surfaces are better radiators then white ones

Which of the following statement is wrong?
(a) Rough surfaces are better radiators tan smooth surfaces
(b) Highly polished mirror surfaces are very good radiators
(c) Black surfaces are better absorbers then white ones
(d) Black surfaces are better radiators then white ones

Grade:Upto college level

2 Answers

Saurabh Koranglekar
askIITians Faculty 10335 Points
3 years ago
Depending on the nature of surfaces the incident radiation falling on the body are either absorbed or reflected. The substances which absorbs more energy that they reflect are known as good absorbers.

Rough surfaces are good absorbers as they absorb more incident radiations while highly mirror polished surfaces reflects more incident radiations, thus they are bad absorbers.

Also, every hot body emits heat radiations from its surface. These radiations depend on nature of the surface, its size and surroundings of the body. The body which emit such radiations is known as Radiator.

A good absorber is a good radiator and a bad absorber is a bad radiator. e.g a black body is one which absorbs all the radiation incident on it and after absorbing the incident radiations.
Black surfaces appear black in colour, independent of the colour of incident radiations. Thus they are better absorbers and radiators than white surfaces.

Therefore, highly polished mirror like surfaces are bad radiators.
Vikas TU
14149 Points
3 years ago
The answer of u r question is...
Option.B
highly polished mirror like surfaces are very good radiators....

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