Four materials A, B, C and D have the following measured absorptive powers at…
PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
Four materials A, B, C and D have the following measured absorptive powers at wavelength 550nm:
A: 0.92 B: 0.36 C: 0.65 D: 0.10.
Each material is fashioned into an identical square plate of area 200cm2 and maintained at a steady temperature of 1000K in an otherwise dark enclosure.
(i) Arrange the four plates in descending order of their emissive powers at 1000K, stating the principle used.
(ii) Which plate will appear brightest to an observer viewing the plates through a small window in the enclosure? Give reasons.
(iii) If all four plates are instead placed in bright sunlight of effective wavelength 550nm for a short interval, which plate will warm up fastest? Explain your choice.