In order to see diffraction,the thickness of the film must be of the order of:

Through a narrow slit of width $2 \,mm$, a diffraction pattern is formed on a screen kept at a distance $2 \,m$ from the slit. The wavelength of the light used is $6330 \mathring{A}$ and it falls normal to the slit and screen. Then, the distance between the two minima on either side of the central maximum is (in $\,mm$)

Red light of wavelength $6500 \, \mathring{A}$ is incident on a slit of width $0.50 \, \text{mm}$. Find the distance between the two first minima on both sides of the central maximum in the diffraction pattern. The distance between the screen and the slit is $1.8 \, \text{m}$.

$A$ beam of light of $\lambda = 600 \, nm$ from a distant source falls on a single slit $1 \, mm$ wide and the resulting diffraction pattern is observed on a screen $2 \, m$ away. The distance between the first dark fringes on either side of the central bright fringe is:

In a single slit diffraction experiment, the first minimum for red light $(660 \ nm)$ coincides with the first secondary maximum of some other wavelength $\lambda$. The value of $\lambda$ is $..... \mathring{A}$.

The radius $r$ of the $n^{th}$ half-period zone is proportional to: