Light is incident on a glass plate `(mu=1.5)` such that angle of refraction is `60^(@)` dark band is observed corresponding to the wavelength of 6000Å. If the thickness of glass plate is `1.2xx10^(-3)` mm. calculate the order of the interference band.

Explanation

To solve the problem step by step, we will follow the necessary calculations to find the order of the interference band.

### Step 1: Convert the given thickness from mm to meters
The thickness of the glass plate \( t \) is given as \( 1.2 \times 10^{-3} \) mm. We need to convert this to meters.

\[ t = 1.2 \times 10^{-3} \text{ mm} = 1.2 \times 10^{-3} \times 10^{-3} \text{ m} = 1.2 \times 10^{-6} \text{ m} \]
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