Three discs, A, B and C having radii 2m, 4m and 6m respectively are coated with carbon black on their outer surfaces. The wavelengths corresponding to maximum intensity are 300 nm, 400 nm and 500 nm, respectively. The power radiated by them are Q_A, Q_B and Q_C respectively.

see full answer

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

$Q_{A}$ is maximum

$Q_{B}$ is maximum

$Q_{A} = Q_{B} = Q_{C}$

$Q_{C}$ is maximum

answer is B.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

According to Wien's law,

$λ_{m} T = b \Rightarrow T \propto \frac{1}{λ_{m}}$

$\Rightarrow T_{A} : T_{B} : T_{C} = \frac{1}{300} : \frac{1}{400} : \frac{1}{500} = 20 : 15 : 12$

According to Stefan's law,

$Q \propto {AT}^{4} \propto R^{2} T^{4}$

$Q_{A} : Q_{B} : Q_{C} = {(2)}^{2} {(20)}^{4} : {(4)}^{2} {(15)}^{4} : {(6)}^{2} {(12)}^{4}$

$= 640000 : 810000 : 746496$

$Q_{B} is maximum$

Watch 3-min video & get full concept clarity