In Fraunhoffer diffraction for single slit central maxima is bright on the both side of it, maxima & minima occurs symmetrically.



For Diffraction Maxima: $a\; sin\theta =\left(2n+1\right)\frac{\lambda }{2}$
For Diffraction Minima: $a\; sin\theta =\text{n}\lambda$

Light of wavelength $\lambda$ passes through a single slit of width $W$ and forms a diffraction pattern on a viewing screen. If this light is then replaced by light of wavelength $2\lambda$, the original diffraction pattern is exactly reproduced if the width of the slit is changed to

Diffraction pattern from a single slit is shown in the figure. The point at which the path difference between two extreme rays from the slit is twice the wavelength is given by the point

A diffraction pattern obtained from a double slit illuminated with monochromatic light is shown in the figure. The dotted line in the figure shows the diffraction envelope while the solid lines give the double slit interference fringes. The experimenter has an arrangement to keep the separation between the slits $\left(d\right)$ fixed, but varies the width of the slits$\left(a\right)$. The intensities of the peaks marked by$1$ and$2$ are $I_1$ and $I_2$ respectively. If the slits are made narrower while keeping the separation fixed, then the ratio $\frac{I_2}{ I_1}$

When the frequency of the light used is changed from $4\times {10}^{14} {\mathrm{s}}^{-1}$ to $5\times {10}^{14} {\mathrm{s}}^{-1}$, the angular width of the principal (central) maximum in a single slit Fraunhofer diffraction pattern changes by $0.6$ radian. What is the width of the slit (assume that the experiment is performed in vacuum)?