25) Two objects A and B have same shape and area. The Emissivity of A is 0.2 and that of B is 0.8 Each radiates same power. The ratio of their absolute temperature. is [2005 M]

$1) 2 : 1 2) 1 : 4 3) 1 : \sqrt{2} 4) \sqrt{2} : 1$

Question

25) Two objects A and B have same shape and area The Emissivity of
A is 0 2 and that of B is 0 8 Each radiates same power The ratio of
their absolute temperature is [2005 M]

1 )   2 : 1 2 )   1 : 4 3 )   1 : 2 4 )   2 : 1

Sayantan · Accepted Answer

Dear Student,

Power radiated by a surface=

P=AεσT4cinsidering the given valus
PAPB=AεAσTA4AεBσTB4or,  PAPB=2×TA48×TB4given, PAPB=1we haveTATB4=41⇒214or, TATB=21

Regards

25) Two objects A and B have same shape and area. The Emissivity of A is 0.2 and that of B is 0.8 Each radiates same power. The ratio of their absolute temperature. is [2005 M] 1 ) 2 : 1 2 ) 1 : 4 3 ) 1 : 2 4 ) 2 : 1

25) Two objects A and B have same shape and area. The Emissivity of A is 0.2 and that of B is 0.8 Each radiates same power. The ratio of their absolute temperature. is [2005 M]

$1) 2 : 1 2) 1 : 4 3) 1 : \sqrt{2} 4) \sqrt{2} : 1$