In Young's double slit experiment,the amplitudes of two sources are $3a$ and $a$ respectively. The ratio of intensities of bright and dark fringes will be (in $:1$)

The width of the fringe is $2\,mm$ on the screen in a double-slit experiment for light of wavelength $400\,nm$. The width of the fringe for light of wavelength $600\,nm$ will be $..............\,mm$.

Laser light $(630 \, nm)$ incident on a pair of slits produces an interference pattern in which the bright fringes are separated by $8.3 \, mm$. $A$ second light produces an interference pattern in which the bright fringes are separated by $7.6 \, mm$. What is the wavelength of this second light in $nm$?

Assertion : No interference pattern is detected when two coherent sources are infinitely close to each other.
Reason : The fringe width is inversely proportional to the distance between the two slits.

What happens to the fringe width in Young's double-slit experiment if it is performed in glycerine instead of air?

In a Young's double-slit experiment,sodium light of wavelength $5890 \ \mathring A$ is used,and the angular width of the fringe is found to be $0.20^\circ$. If the angular width is to be increased by $10\%$,what is the required change in the wavelength?