Very important Short answer type questions of wave optics
Short answer type questions (2 marks )-
1. Define the term wave-front . Use Huygen’s principle to show diagrammatically the propagation of a wave-front from the instant t1 =0 to a later time t2=t .
2. Write the conditions under which light rays said to be coherent . also state why it is necessary to have coherent sources in order to produce an interference pattern ?
3. Based on Huygen’s principle , draw the shape of a plane wave-front as it gets refracted on passing through (i) thin lenses (ii) concave and convex mirror and (iii) prism .
4. What is the effect on the interference fringes in a young’s double slit experiment if a monochromatic light replaced by white light . explain why?
5. In a single-slit diffraction experiment , a monochromatic source of light of wavelength ‘λ’ illuminates a narrow slit of width ‘a’ . shows , Giving appropriate reasoning , that the half angular width of the central maxima in the observed pattern is equal to λ/a .
6. Draw the intensity pattern for single slit diffraction and double slit interference . Hence state two difference between interference and diffraction pattern .
7. Does the appearance of dark fringes in the interference pattern violate , in any way the law of conservation of energy ?
8. Define the term resolving power and limit of resolution . writes its expressions for (i) Telescope (ii) Microscope and (iii) Human eye .
9. Using wave theory of light derive law of reflection or law of refraction ( Snell’s law).
10. How the fringe-width obtained using YDSE changes when (i) separation between slits increases or decreases .(ii) separation between slits and screen changes (iii) entire apparatus is immersed in the liquid having some refractive index.