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QNEET-2013-Ph-1517: NEET 2013 Physics - Class 11 NEET-2013-Ph-1517 Solution: A piece of iron is heated in a flame. It first becomes dull red …
A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using Kirchhoff's Law Newton's Law of cooling Stefan's Law Wien's displacement Law
Multiple Choice Options
- A Kirchhoff's Law
- B Newton's Law of cooling
- C Stefan's Law
- D Wien's displacement Law
Step-by-Step Verified Solution
According to Wien�s displacement law
_ m T = constant
_ m = c o n s t a n t T
So when a piece of iron is heated, _ m decreases i.e. with rise in temperature the maximum intensity of radiation emitted gets shifted towards the shorter wavelengths. So the colour of the heated object will change that of longer wavelength (red) to that of shorter (reddish yellow) and when the temperature is sufficiently high and all wavelengths are emitted, the colour will become white.