Does a body with fixed emissivity become a perfect black body inside an enclosure?

[Abhisuma]

Will a body of given emissivity kept inside a perfect black body start behaving as a perfect black body?

 

[DrClaude]

Why should it?

 

[Abhisuma]

Why should it?

I meant the whole system black body having a normal body inside it

 

[DrClaude]

Are you looking at the blackbody from the outside, or are you interested in the behavior of the grey body inside?

 

[Abhisuma]

Are you looking at the blackbody from the outside, or are you interested in the behavior of the grey body inside?

Can you please answer it for both

 

[DrClaude]

What do you think?

 

[Abhisuma]

What do you think?

I am actually confused.The actual question that my teacher asked was that if I coat a normal ball with lamp black will it start behaving as a perfect black body

 

[DrClaude]

I am actually confused.The actual question that my teacher asked was that if I coat a normal ball with lamp black will it start behaving as a perfect black body

Then go back to the definition of a black body, and think what happens if you look at the painted ball from the outside. Does it behave like a blackbody?

 

[Abhisuma]

Then go back to the definition of a black body, and think what happens if you look at the painted ball from the outside. Does it behave like a blackbody?

A black body is the body that absorbs all radiations falling on it so when a electomagnetic radiation is directed towards the ball the lamp black will absorb it so the ball must behave like a black body.
Am I correct?

 

[DrClaude]

A black body is the body that absorbs all radiations falling on it so when a electomagnetic radiation is directed towards the ball the lamp black will absorb it so the ball must behave like a black body.
Am I correct?

Yes.

 

[Abhisuma]

Yes.

Thanks a lot!