Question

When light of wavelength $\lambda$ falls on a thin film of thick- ness t and refractive index n, the essential conditions for the production of constructive interference fringes by the rays A and B is: (m = 1,2,3,...)

• A.
• B. $2nt\,\cos \,r=m\lambda$
• C. $nt\,\cos \,r=\left( m-\frac{1}{2} \right)\lambda$
• D. $nt\,\cos \,r=m\lambda$

Answer 1

Answer: (A)

Answer 2

Answer (a) $2nt\,\cos \,r=\left( m-\frac{1}{2} \right)\lambda$