The relative luminosity of wavelength $600 \,nm$ is $0.6$. Find the radiant flux of $600 \,nm$ needed to produce the same brightness sensation as produced by $120 \,W$ of radiant flux at $555 \,nm$.

Red light differs from blue light as they have :

Write the difference between the interference pattern and diffraction pattern.

$\lambda_{1}$ and $\lambda_{2}$ are used to illuminate the slits. $\beta_{1}$ and $\beta_{2}$ are the corresponding fringe widths. The wavelength $\lambda_{1}$ can produce photoelectric effect when incident on a metal. But the wavelength $\lambda_{2}$ cannot produce photoelectric effect. The correct relation between $\beta_{1}$ and $\beta_{2}$ is

$A$ circular disc of which $2/3$ part is coated with yellow and $1/3$ part is with blue. It is rotated about its central axis with high velocity,then it will be seen as

Light of different colours propagates through air: