Interference

Step 1: Phase difference for two waves.
For constructive interference, Step 2: Write down the phases.
Then, Step 3: Simplify for maxima.
Step 4: Final Answer.
Hence, the condition for maxima is

Step 1: Thin film interference.
In thin film interference, the condition for maximum reflection is given by For minimum reflection, the condition is Step 2: Minimum thickness calculation.
We use the wavelength for minimum intensity and the refractive index to calculate the minimum thickness of the film. We substitute into the equation for minimum reflection with : Simplifying, we find Final Answer: The minimum thickness of the film is

Step 1: Relation between fringe shift and refractive index.
Number of fringes shifted Step 2: Substitute the known values.

Step 3: Final Answer.
Refractive index