$A$ 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 temperature of a furnace is $200\,^{\circ}C$. In its spectrum,the maximum intensity is obtained at about $400\,\mathring{A}$. If the maximum intensity is at $200\,\mathring{A}$,calculate the temperature of the furnace in $^{\circ}C$. ......... $^{\circ}C$

$A$ black body emits radiations of maximum intensity at a wavelength of $5000 \mathring A$,when the temperature of the body is $1227^{\circ}C$. If the temperature of the body is increased by $1000^{\circ}C$,the maximum intensity of emitted radiation would be observed at..... $\mathring A$.

Three stars $A, B, C$ have surface temperatures $T_{A}, T_{B}, T_{C}$ respectively. Star $A$ appears bluish,star $B$ appears reddish,and star $C$ appears yellowish. Hence,

If the temperature of the sun becomes twice its present temperature,then

Which graph represents the $v_m - T$ relationship for a black body,where $v_m$ is the frequency corresponding to the maximum energy emission and $T$ is the absolute temperature?