Question

# The amount of heat radiated per second by a body of surface area 20 cm2 kept at temperature 27oC is H and wavelength having maximum share of emission is λ, find H and λ  approximately (e = emissivity = 0.6,         σ=6×10−6wattm2K4 Wein's constant =0.288 cm−K)

A
H=58 watt, λ=0.44×103 cm
B
H=68 watt, λ=0.96×103 cm
C
H=58 watt, λ=0.96×103 cm
D
H=68 watt, λ=0.44×103 cm

Solution

## The correct option is B H=58 watt, λ=0.96×10−3 cmH=σeAT4     =6×10−6×0.6×20×10−4×(300)4     =6×10−6×12×10−4×81×108     =81×6×12×10−2≈58 watt Also, λm.T=0.288 cm−K λm=.288300cm=0.96×10−3cm

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