On increasing the temperature of a substance gradually, which of the following colours will be noticed by you?

The spectral emissive power $E_\lambda$ for a body at temperature $T_1$ is plotted against the wavelength and the area under the curve is found to be $A$. At a different temperature $T_2$,the area is found to be $9A$. Then $\lambda_1/\lambda_2 =$

$A$ black body at a temperature of $3000 \ K$ cools down. The wavelength corresponding to maximum energy density shifts by $\Delta \lambda = 9 \ \mu m$. What is the new temperature of the black body (in $K$)? (Given $b = 3 \times 10^{-3} \ m \cdot K$)

$A$ black disc has a radius $R$ and the wavelength corresponding to the maximum intensity is $\lambda$. The emissive power $(E)$ for the different radii and maximum wavelengths is directly proportional to:

Ordinary bodies $P$ and $Q$ radiate maximum energy with a wavelength difference of $3 \mu m$. The absolute temperature of body $P$ is four times that of $Q$. The wavelength at which body $Q$ radiates maximum energy is (in $\mu m$)

The wavelength corresponding to the maximum energy emitted by a body at a certain temperature is ${\lambda _0}$. If the temperature of the body is increased such that the new maximum wavelength becomes $\frac{3{\lambda _0}}{4}$, then by what factor does the emissive power increase?