A small square plate of side 5.0 cm is maintained at a temperature such that the peak…
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A small square plate of side 5.0 cm is maintained at a temperature T1 such that the peak of its blackbody spectrum lies at 750 nm. Another identical plate has its peak at 375 nm.
(i) Determine the absolute temperatures T1 and T2 corresponding to the two plates. (Use b=2.9×10−3mK.)
(ii) Find the ratio of the radiant power emitted by the second plate to that emitted by the first plate.
(iii) Calculate the numerical value of the additional radiant power (in watts) emitted by the second plate compared with the first.
(iv) State the region of the electromagnetic spectrum (infra-red, visible, or ultraviolet) in which each peak lies and comment on the practical consequence for the colour or invisibility of the emitted radiation.