A thick glass slab `(mu= 1.5)` is to be viewed in reflected white light. It is proposed to coat the slab with a thin layer of a material having refractive index 1.3 so that the wavelength 6000 Å os suppressed. Find the minimum thickness of the coating required.

Explanation

To find the minimum thickness of the coating required to suppress the wavelength of 6000 Å in reflected white light, we will use the principle of destructive interference. Here’s the step-by-step solution:

### Step 1: Understand the Condition for Destructive Interference
For destructive interference to occur, the optical path difference (OPD) between the two waves must be equal to an odd multiple of half the wavelength. The condition can be expressed as:
\[ \text{OPD} = (2n - 1) \frac{\lambda}{2} \]
where \( n \) is an integer.
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