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

$A$ single slit of width $a$ is illuminated by a monochromatic light of wavelength $600 \, nm$. The value of $a$ for which the first minimum appears at $\theta = 30^{\circ}$ on the screen will be ........... $\mu m$.

$A$ parallel beam of monochromatic light falls normally on a single narrow slit. The angular width of the central maximum in the resulting diffraction pattern

$A$ parallel beam of monochromatic light of wavelength $600 \,nm$ passes through a single slit of $0.4 \,mm$ width. The angular divergence corresponding to the second-order minima would be $...... \times 10^{-3} \,rad$.

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

In Fraunhofer diffraction by a single slit,if the slit width is $a$,the wavelength is $\lambda$,and the focal length of the lens is $f$,what is the linear width of the central maximum?