MHT CET2009PhysicsWave Optics
If fringe width is 0.4 ~mm , the distance between fifth bright and third dark band on same side is
Options
- A1 ~mm
- B2 ~mm
- C3 ~mm
- D4 ~mm
Correct answer
A. 1 ~mm
Step-by-step solution
Position of n th bright fringe from central array l maxima x_ r₁ = n₁ D d here n₁=5 x_ n₄ = 5 D d array Position of n th dark fringe from central maxima aligned x_ n &= (2 n-1) D 2 d , Here n=3 x_ n &= 5 2 D d x_ r₄ -x_ n &= 2.5 D d =2.5 aligned Given =0.4 ~mm x_ n₁ -x_ n =1 ~mm