$A$ 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?

Assertion: The colour of a green flower seen through red glass appears to be dark.
Reason: Red glass transmits only red light.

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

$A$ monochromatic light source of wavelength $\lambda$ is placed at $S$. Three slits $S_1, S_2$ and $S_3$ are equidistant from the source $S$ and the point $P$ on the screen. $S_1P - S_2P = \lambda / 6$ and $S_1P - S_3P = 2\lambda / 3$. If $I$ is the intensity at $P$ when only one slit is open,the intensity at $P$ when all the three slits are open is

$A$ zone plate of focal length $60\,cm$ behaves as a convex lens. If the wavelength of incident light is $6000\,\mathring{A},$ then the radius of the first half-period zone will be:

Write the difference between the interference pattern and diffraction pattern.