The expected graphical representation of the variation of angle of deviation `'delta'` with angle of incidence 'i' in a prism is :

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Answer

To solve the problem of the graphical representation of the variation of angle of deviation (Δ) with angle of incidence (i) in a prism, we need to understand the relationship between these two angles.

### Step-by-Step Solution:

1. **Understanding the Relationship**:
- The angle of deviation (Δ) is the angle by which light is deviated from its original path after passing through a prism.
- As the angle of incidence (i) increases, the angle of deviation (Δ) initially decreases.

2. **Minimum Deviation**:
- There exists a specific angle of incidence (i_min) at which the angle of deviation (Δ) reaches its minimum value (Δ_min). This is a critical point in the graph.

3. **Behavior Beyond Minimum Deviation**:
- After reaching the minimum deviation, if the angle of incidence continues to increase, the angle of deviation starts to increase again. This means that beyond i_min, Δ increases with increasing i.

4. **Graphical Representation**:
- The graph starts with Δ decreasing as i increases, reaches a minimum value at i_min, and then starts to increase again as i continues to increase.
- Therefore, the graph has a U-shaped curve, where the lowest point corresponds to the minimum deviation.

5. **Conclusion**:
- The expected graphical representation of the variation of angle of deviation Δ with angle of incidence i in a prism is a curve that decreases to a minimum point and then increases again.