Physics · Optics, Nature of Light and Optical Instruments

When we use white light in place of monochromatic light then only the central fringe looks white and other fringes of different colors are observed. The difference in path lengths, being zero at the center gives zero phase difference at the center for all wavelengths hence making the center fringe white. It is because the central fringe for all colors is formed at the center point so it becomes white after mixing up. As fringes of other colors fall at different places we see fringes of all colors on the central bright fringe. At other different points on the screen, the phase difference is given by ϕ=kΔx=2π/​λΔx where Δx is the difference in path lengths. Since λ is different for different colors, the fringe width will be different for each color and hence all other fringes will be colored. The red color will be observed further away from it because it has a shorter wavelength. 

When we use white light in place of monochromatic light then only the central fringe looks white and other fringes of different colors are observed. The difference in path lengths, being zero at the center gives zero phase difference at the center for all wavelengths hence making the center fringe white. It is because the central fringe for all colors is formed at the center point so it becomes white after mixing up. As fringes of other colors fall at different places we see fringes of all colors on the central bright fringe. At other different points on the screen, the phase difference is given by ϕ=kΔx=2π/​λΔx where Δx is the difference in path lengths. Since λ is different for different colors, the fringe width will be different for each color and hence all other fringes will be colored. The red color will be observed further away from it because it has a shorter wavelength. 

When we use white light in place of monochromatic light then only the central fringe looks white and other fringes of different colors are observed. The difference in path lengths, being zero at the center gives zero phase difference at the center for all wavelengths hence making the center fringe white. It is because the central fringe for all colors is formed at the center point so it becomes white after mixing up. As fringes of other colors fall at different places we see fringes of all colors on the central bright fringe. At other different points on the screen, the phase difference is given by ϕ=kΔx=2π/​λΔx where Δx is the difference in path lengths. Since λ is different for different colors, the fringe width will be different for each color and hence all other fringes will be colored. The red color will be observed further away from it because it has a shorter wavelength. 

When we use white light in place of monochromatic light then only the central fringe looks white and other fringes of different colors are observed. The difference in path lengths, being zero at the center gives zero phase difference at the center for all wavelengths hence making the center fringe white. It is because the central fringe for all colors is formed at the center point so it becomes white after mixing up. As fringes of other colors fall at different places we see fringes of all colors on the central bright fringe. At other different points on the screen, the phase difference is given by ϕ=kΔx=2π/​λΔx where Δx is the difference in path lengths. Since λ is different for different colors, the fringe width will be different for each color and hence all other fringes will be colored. The red color will be observed further away from it because it has a shorter wavelength. 

When we use white light in place of monochromatic light then only the central fringe looks white and other fringes of different colors are observed. The difference in path lengths, being zero at the center gives zero phase difference at the center for all wavelengths hence making the center fringe white. It is because the central fringe for all colors is formed at the center point so it becomes white after mixing up. As fringes of other colors fall at different places we see fringes of all colors on the central bright fringe. At other different points on the screen, the phase difference is given by ϕ=kΔx=2π/​λΔx where Δx is the difference in path lengths. Since λ is different for different colors, the fringe width will be different for each color and hence all other fringes will be colored. The red color will be observed further away from it because it has a shorter wavelength.