question_answer

Draw the diagram showing intensity distribution of light on the screen for diffraction of light at a single slit. How is the width of central maxima affected if (i) the width of the slit is doubled; (ii) the wavelength of the light used is increased? What happens to the width of the central maxima if the whole apparatus is immersed in water and why?          

Answer:

                For intensity distribution of light in diffraction at a signal slit, see Fig.                 Width of central maximum is given by \[{{\beta }_{0}}=\frac{2D\lambda }{d}\] (i) When wavelength\[(\lambda )\] of light used is increased, the width of central maximum increases. (ii) When width (d) of the slit is increased, the width of central maximum decreases. Wavelength of light in water decreases, so width of central maximum also decreases.