Molten iron just tapped from a blast furnace emits radiation whose intensity peaks at…
PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
Molten iron just tapped from a blast furnace emits radiation whose intensity peaks at a wavelength of 950nm. Two minutes later, after partial cooling in air, the peak of its radiation curve is found at 1100nm. Take b=2.9×10−3mK.
(i) Calculate the temperature of the molten iron at the instant of tapping and after the two-minute cooling period.
(ii) Determine the average rate of fall of temperature, in Kmin−1, during this interval.
(iii) Assuming the emissive power per unit area of the surface varies as the fourth power of its absolute temperature, by what factor has the emissive power changed over the two minutes?