Interference pattern with Young's double slits 1.5mm apart are formed on a screen at a distance 1.5m from the plane of slits. In the path of the beam of one of the slits, a transparent film of 10 micron thickness and of refractive index 1.6 is interposed while in the path of the beam from the older slit a transparent film of 15 micron thickness and of refractive index 1.2 is interposed. Find the displacement of the fringe patten.

Explanation

To solve the problem of finding the displacement of the fringe pattern due to the introduction of two transparent films in a Young's double-slit experiment, we will follow these steps:

### Step 1: Understand the setup
We have two slits that are 1.5 mm apart, and they create an interference pattern on a screen that is 1.5 m away from the slits. A transparent film is placed in front of each slit, affecting the path length of the light coming from each slit.

### Step 2: Identify the parameters
- Distance between the slits (d) = 1.5 mm = 1.5 × 10^-3 m
- Distance from the slits to the screen (D) = 1.5 m
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