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
The color change in the heated iron from dull red to reddish yellow to white hot can be explained using Wein's Displacement Law. This law states that the wavelength (\(\lambda_{max}\)) at which the maximum emission occurs is inversely proportional to the absolute temperature \(T\) of the object:
\[
\lambda_{max} \propto \frac{1}{T}
\]
As the iron's temperature increases, the peak wavelength of emitted radiation shifts toward shorter wavelengths (from red to yellow and eventually to white, which is a combination of all visible wavelengths). Thus, the observed color change corresponds to an increase in temperature, with shorter wavelengths being emitted at higher temperatures.