Question

a copper sphere has surface area 3.142*20-2 m2& it's emissivity is 0.018 find energy lost by the sphere per second when it's temp is 100°C​

Answer 1

Explanation:

ANSWER

The heat loss due to radiation will cause temperature to fall. Hence,

eσAT

4

=

dt

dQ

Since dQ=mCdT

eσ(4πr

2

)T

4

=

dt

ρ(

3

4

πr

3

)CdT

ρrC

3eσ

t=∫

200

100

T

4

dT

t=

9eσ

ρrC

(1−

8

1

)10

−6

=

72eσ

7ρrC

10

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