Ac cording to Stefan' law of radiation, a black body radiates energy `sigma
Channel: Doubtnut
Date: 2020-08-16

Ac cording to Stefan' law of radiation, a black body radiates energy `sigma T^4` from its unit  surface area every second where T is the surface temperature of the black body and `sigma = 5.67 xx 10^(-8) W//m^2 K^4` is known as Stefan's constant. A nuclear weapon may be thought of as a ball of radius 0.5 m When detoneted, it reachs temperature of `10^6 K` and can be treated as a black body. (a) Estimate the power it radiates. (b) if surrounding has water at `30^@C` how much water can 10% of the energy produced evaporate in 1s ? ` [s_w = 4186.0 J//Kg K and L_(upsilon) = 22.6 xx 10^5 J//kg]` (c ) If all this energy U is in the form of radiation, corresponding momentum is ` p = U//c.` How much momentum per unit time does it impart on unit area at a distance of 1 km ?