A black body radiates heat energy at the rate of 2 x 105J/s-m2at 400 K...
Given: Rate of heat radiation at temperature T1 = 2 x 10^5 J/s-m^2
Rate of heat radiation at temperature T2 = 32 x 10^5 J/s-m^2
We need to find the temperature T2.
We can use the Stefan-Boltzmann law which states that the rate of heat radiation from a black body is proportional to the fourth power of its absolute temperature.
Mathematically,
P = σAεT^4
Where P is the rate of heat radiation, A is the surface area of the black body, ε is the emissivity of the black body (which is 1 for a black body), σ is the Stefan-Boltzmann constant (5.67 x 10^-8 W/m^2-K^4), and T is the absolute temperature.
Using this formula, we can write:
T2^4/T1^4 = (32 x 10^5)/(2 x 10^5)
Simplifying this equation, we get:
T2^4 = 256T1^4
Taking the fourth root on both sides, we get:
T2 = (256T1^4)^(1/4)
T2 = T1 x 4
Substituting the given values, we get:
T2 = 400 K x 4
T2 = 1600 K
Therefore, the temperature at which the rate of heat radiation is 32 x 10^5 J/s-m^2 is 1600 K, which is option D.
A black body radiates heat energy at the rate of 2 x 105J/s-m2at 400 K...
E proportional to T^4
2×10^5/32×10^5 =400^4/t^4
ie, t=2×400=800
option d is answer