A ray reflected successively from two plane mirrors inclined at a certain angle `(lt 90^(@))` undergoes a deviation of `300^(@)` . The number of images observable are:

Options

A. 10
B. 11
C. 12
D. 14

Explanation

To solve the problem of finding the number of images formed by two plane mirrors inclined at an angle, we can follow these steps:

### Step-by-step Solution:

1. **Understanding the Problem**: We have two plane mirrors inclined at an angle \( \theta \) (which is less than \( 90^\circ \)). A ray of light reflects off these mirrors and undergoes a total deviation of \( 300^\circ \).

2. **Using the Deviation Formula**: The formula for the total deviation \( O \) when a ray is reflected from two mirrors is given by:
\[ O = 360^\circ - 2\theta \]
Here, \( O \) is the total deviation, and \( \theta \) is the angle between the two mirrors.

3. **Setting Up the Equation**: We know from the problem that the total deviation \( O \) is \( 300^\circ \). Therefore, we can set up the equation:
\[ 300^\circ = 360^\circ - 2\theta \]

4. **Solving for \( \theta \)**: Rearranging the equation to solve for \( \theta \):
\[ 2\theta = 360^\circ - 300^\circ \]
\[ 2\theta = 60^\circ \]
\[ \theta = 30^\circ \]

5. **Calculating the Number of Images**: The number of images \( n \) formed by two mirrors inclined at an angle \( \theta \) can be calculated using the formula:
\[ n = \frac{360^\circ}{\theta} - 1 \]
Substituting \( \theta = 30^\circ \):
\[ n = \frac{360^\circ}{30^\circ} - 1 \]
\[ n = 12 - 1 \]
\[ n = 11 \]

6. **Conclusion**: The number of images observable is \( 11 \).

### Final Answer:
The number of images observable is **11**.