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A white-hot metal wire at 3000 K has a r...

A white-hot metal wire at 3000 K has a radius of 0.075 cm. Calculate the rate per unit length at which it emits radiation if its emissivity is 0.35. Ignore the radiation it receives from the surroundings. Take Stefan'sconstant `sigma=5.7xx10^(-8)W//m^(2)K.`

Text Solution

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Radiation rate `=sigmaeAT^(4)` (here we use `A=2pirasl=1m`)
`=5.7xx10^(-8)xx0.35xx2xx3.14xx0.075xx10^(-2)xx(3000)^(4)`
`=7611.12W//m`
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