CBSE NOTES CLASS 12 PHYSICS
CHAPTER 10 WAVE OPTICS
When can we consider the light beam to be parallel beam in single slit experiment?
- We can consider the two or more paths from the slits to the screen as parallel only if the screen on which the fringes are formed is at a large distance, i.e. a << D.
- Alternatively, this situation can be obtained by placing a convex lens after the slit and putting the screen at its focus.
Advantages of lens
- The lens does not introduce any extra path differences in a parallel beam.
- This arrangement gives more intensity than placing the screen far away.
Angular size and size on the screen
- The separation of the central maximum from the first null of the diffraction pattern is by an angle . This size on the screen will be .