Diffraction of light occurs only when the dimension of the obstacle is .....

The phenomenon of diffraction was discovered by ...... .

Light of wavelength $5000 \, \text{Å}$ is incident on a slit of width $0.1 \, \text{mm}$. Find the width of the central bright fringe on a screen placed at a distance of $2 \, \text{m}$ in $\text{mm}$.

In a single slit diffraction experiment, for wavelength $\lambda$, the half angular width of the central maximum is $\theta$. For a wavelength $p\lambda$, the half angular width of the central maximum is $q\theta$. What is the ratio of the half angular widths of the first secondary maximum in the first case to the second case?

In a Fraunhofer diffraction at a single slit,if yellow light illuminating the slit is replaced by blue light,then the diffraction bands

When a compact disc is illuminated by a source of white light,coloured 'lanes' are observed. This is due to