In the experiment of diffraction due to a single slit, if the slit width is decreased, the width of the central maximum

In biprism experiment, if $$5^{\text {th }}$$ bright band with wavelength $$\lambda_1^{\prime}$$ coincides with $$6^{\text {th }}$$ dark band with wavelength $$\lambda_2{ }^{\prime}$$ then the ratio $$\left(\frac{\lambda_2}{\lambda_1}\right)$$ is

In Young's double slit experiment, the two slits are 'd' distance apart. Interference pattern is observed on a screen at a distance 'D' from the slits. A dark fringe is observed on a screen directly opposite to one of the slits. The wavelength of light is

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