The angle of a prism is `30^(@)`. The rays incident at `60^(@)` on one refracting face suffer a deviation of `30^(@)`. Then the angle of emergence is :

Options

A. `0^@`
B. `30^@`
C. `60^@`
D. `90^@`

Answer

To solve the problem, we need to find the angle of emergence (E) from a prism given the angle of the prism (A), the angle of incidence (i), and the deviation (D).

### Step-by-Step Solution:

1. **Identify Given Values:**
- Angle of the prism, \( A = 30^\circ \)
- Angle of incidence, \( i = 60^\circ \)
- Deviation, \( D = 30^\circ \)

2. **Understand the Relation of Angles:**
- The deviation \( D \) is given by the formula:
\[ D = i + e - A \]
- Here, \( e \) is the angle of emergence.

3. **Substituting Known Values:**
- Substitute the known values into the deviation formula:
\[ 30^\circ = 60^\circ + e - 30^\circ \]

4. **Simplifying the Equation:**
- Rearranging the equation gives:
\[ 30^\circ = 60^\circ + e - 30^\circ \]
- This simplifies to:
\[ 30^\circ = 30^\circ + e \]

5. **Isolating the Angle of Emergence:**
- Subtract \( 30^\circ \) from both sides:
\[ 0^\circ = e \]

6. **Conclusion:**
- Therefore, the angle of emergence \( e = 0^\circ \).

### Final Answer:
The angle of emergence is \( 0^\circ \).

---