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A body of surface area 10 cm^(2) and te...

A body of surface area `10 cm^(2)` and temperature ` 727 ^(@) C` emits 600 J of enrgy per minute. Find its emissivity.

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T = 273 + 72 7 = 1000 K , t = 1 minute = 60 s , `simga = 5.67 xx 10^(-8) "W/m"^(2) . K^(4) Q= e A simgaT^(4) t`
The emissivity ` =e (Q)/(A sigma T^(4)t) = 600/( 10^(-3) xx 5.67 xx 10^(-8) xx (10^(3))^(4) xx 60)`
` 10/(5.67 xx 10) = 10/56.7 = 0.1764`
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