A ray of light is incident normally on one of the refracting surfaces of a prism of refracting angle A. The emergent ray grazes the other refracting surface. Find the refractive index of the material of the prism.

Explanation

To solve the problem of finding the refractive index of the material of the prism when a ray of light is incident normally on one of the refracting surfaces and the emergent ray grazes the other refracting surface, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Incident Ray**:
- The ray of light is incident normally on one of the refracting surfaces of the prism. When light is incident normally, the angle of incidence \( I_1 \) is \( 0^\circ \).
- Therefore, the angle of refraction \( R_1 \) at the first surface is also \( 0^\circ \) (since it passes straight through).

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