COMEDK2019PhysicsWave Optics
In Young's double slit experiment, if monochromatic light used is replaced by white light, then
Options
- Aall bright fringes become white
- Ball bright fringes have colours between violet and red
- Cno fringes are observed
- Donly central fringe is white, all other fringes are coloured
Correct answer
D. only central fringe is white, all other fringes are coloured
Step-by-step solution
White light consists inumerable wavelengths. If monochromatic light is replaced by white light in Young's double slit experiment, then each wavelength form their separate interference pattern. The resultant effect of all these patterns is obtained on the screen. The waves of all colours reach at mid-point with same or zero phase difference. Therefore, central fringe is white. As fringe width i.e. wavelength increases in order of colours denoted by VIBGYOR, therefore on either side of it some coloured fringes are ob