Light is incident on a glass plate $(\mu = 1.5)$ such that the angle of refraction is $60^\circ$. $A$ dark band is observed corresponding to a wavelength of $6000 \, \mathring A$. If the thickness of the glass plate is $1.2 \times 10^{-3} \, mm$,find the order of the interference band.

In a biprism experiment,the $4^{\text{th}}$ dark band is formed opposite to one of the slits. The wavelength of light used is ($D=$ distance between source and screen,$d=$ distance between the slits).

The thickness of a plate having refractive index $\mu$ which will produce a change in optical path equal to half the wavelength $\lambda$ of the light passing through it is

When a mica sheet of thickness $7 \ \mu m$ and refractive index $\mu = 1.6$ is placed in the path of one of the interfering beams in a biprism experiment, the central fringe shifts to the position of the seventh bright fringe. The wavelength of the light used is $............ \ \mathring{A}$.

In a biprism experiment,the $6^{\text{th}}$ bright band with wavelength $\lambda_1$ coincides with the $7^{\text{th}}$ dark band with wavelength $\lambda_2$. Then the ratio $\lambda_1 : \lambda_2$ is (other settings remain the same):

In a biprism experiment, the distance of the source from the biprism is $1 \, m$ and the distance of the screen from the biprism is $4 \, m$. The refracting angle of the biprism is $\alpha = 2 \times 10^{-3} \, \text{radians}$. The refractive index $\mu$ of the biprism is $1.5$ and the wavelength of light used is $\lambda = 6000 \, \mathring{A}$. How many fringes will be seen on the screen?