A piece of iron is heated in a flame. It first become dull red then becomes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using :

Newton’s law of cooling  Stefan’s law  Wien’s law Kirchhoff’s law

Wien’s law

By using Wien’s displacement law λmT = . we can say that temperature and wavelength are related. Hence the above observation can be correctly answered by it.