If a graph is plotted by taking spectral emissive power along $y$-axis and wavelength along $x$-axis,then the area under the graph above the wavelength axis is ...........

The black discs $x, y$ and $z$ have radii $1 \ m, 2 \ m$ and $3 \ m$ respectively. The wavelengths corresponding to maximum intensity are $200 \ nm, 300 \ nm$ and $400 \ nm$ respectively. The relation between emissive power $E_{x}, E_{y}$ and $E_{z}$ is

When an iron rod is heated, the variation of colour from dull red to white can be explained by

The intensity of radiation emitted by the sun has its maximum value at a wavelength of $510\;nm$ and that emitted by the north star has the maximum value at $350\;nm$. If these stars behave like black bodies,then the ratio of the surface temperature of the sun and north star is

We consider the radiation emitted by the human body. Which of the following statements is true?

Observations of light from three different stars $A, B$,and $C$ show that the intensity of the red color is maximum for star $A$,the intensity of the blue color is maximum for star $B$,and the intensity of the yellow color is maximum for star $C$. Which of the following conclusions can be drawn from these observations?