Temperature of black body is `3000K`. When black body cools, then change in wevelength `Deltalambda = 9` micron corresponding to maximum energy density. Now temperature of black body is :-

Options

A. `290K`
B. `2700K`
C. `270K`
D. `1800K`

Answer

A

Explanation

When's displacement law.
`lambda_(1)T_(1) = lambda_(2)T_(2) = b = 2.8 xx 10^(-3)` km
`implies 3000 xx lambda_(1) = T_(2) xx (lambda_(2)) cong 3 xx 10^(-3)` km
`implies lambda_(1) = 1mum` & `[lambda_(2)-lambda_(1)] = 9 mum`
`implies lambda_(2) = 10mum`
`implies T_(2) = 300K`