White light reflected from a soap film (Refractive Index =1.5 ) has a maxima at 600 ~nm and a minima at 450 ~nm with no minimum in between. Then the thickness of the film is

Step-by-step solution

We know for maxima 2 t r= (2 n+1) ₁ 2 ...(i) For minima 2 t r=(n+1) ₂...(ii) Given here, ₁=600 ~nm and ₂=450 ~nm Dividing Eq. (i) by (ii) and substituting values of ₁ and ₂ , we get aligned (2 n+1) ₁ 2(n+1) ₂ &=1 90 m+90 &=60 n+60 30 n &=30 n &=1 aligned Using one of the equation, we get In given condition 2 t=(2 n+1) 2 gathered 2 1.5 t=(2 1+1) 600 2 3 t= 3 600 2 t=300 ~nm =3 10⁻⁶ ~m =3 units gathered