In the diffraction due to a single slit,the central fringe ...

In the diffraction pattern of a single slit,the width of the secondary maxima compared to the central maximum is:

To observe diffraction,the size of an obstacle:

$A$ parallel beam of light of wavelength $\lambda$ is incident normally on a narrow slit. $A$ diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the second minimum of the diffraction pattern,the phase difference between the rays coming from the two edges of the slit is:

$A$ parallel beam of monochromatic light of wavelength $5000 \; \mathring{A}$ is incident normally on a single narrow slit of width $0.001 \; mm$. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to ........$^o$.

The diffraction fringes obtained by a single slit are of