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 $555 \,nm$.

Properly arrange the effects with their reasons:

Effects	Reasons
$(i)$ Rainbow formation	$(a)$ Reflection
$(ii)$ Red colour of danger signals	$(b)$ Scattering
$(iii)$ Different colours of thin oil film and soap bubbles	$(c)$ Chromatic aberration
$(iv)$ Coloured images formed by lenses	$(d)$ Dispersion
$(v)$ Different colours of clouds	$(e)$ Interference

Fraunhofer lines are produced by the absorption of light in

$A$ source emits light of wavelengths $4700 \ \mathring{A}$,$5400 \ \mathring{A}$,and $6500 \ \mathring{A}$. The light passes through red glass before being tested by a spectrometer. Which wavelength is seen in the spectrum?

Column $I$ shows four situations of standard Young's double slit arrangement with the screen placed far away from the slits $S_1$ and $S_2$. In each of these cases $S_1 P_0 = S_2 P_0$,$S_1 P_1 - S_2 P_1 = \lambda / 4$ and $S_1 P_2 - S_2 P_2 = \lambda / 3$,where $\lambda$ is the wavelength of the light used. In the cases $B, C$ and $D$,a transparent sheet of refractive index $\mu$ and thickness $t$ is pasted on slit $S_2$. The thicknesses of the sheets are different in different cases. The phase difference between the light waves reaching a point $P$ on the screen from the two slits is denoted by $\delta(P)$ and the intensity by $I(P)$. Match each situation given in Column $I$ with the statement$(s)$ in Column $II$ valid for that situation.

Column $I$	Column $II$
$(A)$ No sheet	$(p)$ $\delta(P_0) = 0$
$(B)$ $(\mu-1)t = \lambda / 4$	$(q)$ $\delta(P_1) = 0$
$(C)$ $(\mu-1)t = \lambda / 2$	$(r)$ $I(P_1) = 0$
$(D)$ $(\mu-1)t = 3\lambda / 4$	$(s)$ $I(P_0) > I(P_1)$
	$(t)$ $I(P_2) > I(P_1)$

The figure shows a schematic diagram of Young's Double Slit Experiment. If the distance $D$ between the slits and the screen is varied,choose the correct statement$(s)$.