A prism is made of glass of unknown refractive index. A parallel beam of light is incident on a face of the prism. By rotating the prism, the minimum angle of deviation is measured to be `40^@`. What is the refractive index of the prism ? If the prism is placed in water `(mu = 1.33)`, predict the new angle of minimum deviation of the parallel beam. The refracting angle of prism is `60^@`.

Explanation

To solve the problem step by step, we will follow the principles of optics related to prisms and the refractive index.

### Step 1: Understand the given data
We have the following information:
- Minimum angle of deviation (δ) = 40°
- Refracting angle of the prism (A) = 60°
- Refractive index of water (μ_water) = 1.33

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