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The top of an insulated cylindrical cont...

The top of an insulated cylindrical container is covered by a disc having emissivity 0.6 and conductivity 0.167 `"WK"^(– 1)m^(–1)` and thickness 1 cm. The temperature is maintained by circulating oil as shown in figure. Find the radiation loss to the surrounding in `"Jm"^(–2)s^(–1 )`if temperature of the upper surface of the disc is `127^(@)"C"` and temperature of the surrounding is `27^(@)"C"`.

A

`595 J//m^2 xx s`

B

`595 cal//m^2 xx s`

C

`991.0 J// m^2 xx s`

D

`440 J//m^2 xx s`

Text Solution

Verified by Experts

The correct Answer is:
A
Rate of heat loss per unit area due to radiation i.e. emissive power (e) = `epsilon sigma (T^4-T_0^4)`
`=0.6 xx (17)/(3) xx 10^(-8) xx [(400)^4-(300)^4]=595 J//m^2`sec.
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