In a Young's double slit experiment,$12$ fringes are observed to be formed in a certain segment of the screen when light of wavelength $600 \ nm$ is used. If the wavelength of light is changed to $400 \ nm$,the number of fringes observed in the same segment of the screen is:

In Young's double slit experiment,when two light waves form the third minimum,they have:

In a double-slit experiment,the angular width of the fringes is $0.20^o$ for sodium light $(\lambda = 5890 \ \mathring{A})$. In order to increase the angular width of the fringes by $10\%$,the necessary change in the wavelength is:

If the source of light used in a Young's double slit experiment is changed from red to violet:

$A$ beam of light consisting of two wavelengths $650 \, nm$ and $520 \, nm$ is used to illuminate the slits of a Young's double-slit experiment. The order of the bright fringe of the longer wavelength that coincides with a bright fringe of the shorter wavelength at the least distance from the central maximum is:

In a $YDSE$ with two identical slits,when the upper slit is covered with a thin,perfectly transparent sheet of mica,the intensity at the centre of the screen reduces to $75\%$ of the initial value. The second minimum is observed to be above this point and the third maximum below it. Which of the following cannot be a possible value of the phase difference caused by the mica sheet?