Transmission Of Heat Question 258
Question: If black wire of platinum is heated, then its colour first appear red, then yellow and finally white. It can be understood on the basis of
[MP PMT 1984]
Options:
A) Wien’s displacement law
B) Prevost theory of heat exchange
C) Newton’s law of cooling
D) None of the above
Show Answer
Answer:
Correct Answer: A
Solution:
According to Wein’s law $ {\lambda _{m}}T $ = constant, on heating up to ordinary temperatures, only long wavelength (red) radiation is emitted. As the temperature rises, shorter wavelengths are also emitted in more and more quantity. Hence the colour of radiation emitted by the hot wire shifts from red to yellow, then to blue and finally to white.
BETA
