The intensity of radiation emitted by the sun has its maximum value at a wavelenght of `510 nm` and that emitted by the north star has the maximum value at `350 nm` If these stars behave like balackbodies the nthe ratio of the surface temperature of the sun and the north star is .

Options

A. `1.46`
B. `0.69`
C. `1.21`
D. `0.83`

Answer

B

Explanation

According to Wien's displacment law
`lambda_(m) T =` constant (b) Let S =Sun,NS = North star
`:. (lamda_(m))_(s)T_(s)=(lambda_(m))_(NS)T_(NS)`
`:. (T_(s))/(T_(NS))=(lambda_(m))_(NS)/((lambda_(m))_(S))=(350)/(510)=0.69`
The workdone `W` is positive if volume inreases in the process and `W` is negative if volume decreases in the process Hence `W_(AB)` is positive as volume increases from `V_(1)` to `V_(2), W_(BC)` is negative as volume decreases from `V_(2)` to `V_(1)`
Further `|W_(bc)|gt|W_(AB)|` Net workdone `= W_(AB) + (-W_(BC))`
`W=A` negative value `( :' |W_(BC)|gt|W_(AB)|) or W lt 0`
From the graph itself `P_(3) gt P_(1) :. W gt 0` and `P_(3) gt P_(1)`
Hence option (c) represents correct answer
.