From the following which can convert an incident light from a point source into parallel beam?

Options

A. Concave mirror and concave lens both
B. Concave mirror and convex lens both
C. Convex mirror and convex lens both
D. Perpendicularly placed two plane mirrors

Explanation

To solve the question of which optical device can convert incident light from a point source into a parallel beam, we will analyze the options provided.

### Step-by-Step Solution:

1. **Understanding the Concept**:
- A point source emits light in all directions. When this light passes through certain optical devices, it can be transformed into a parallel beam.

2. **Analyzing the Options**:
- **Option 1: Concave Mirror and Convex Lens**:
- A concave mirror can take light rays from a point source and reflect them to form parallel rays when the object is placed at its focus.
- A convex lens can take light rays from a point source and refract them to form parallel rays when the object is placed at its focal point.
- **Option 2: Concave Mirror and Concave Lens**:
- A concave lens diverges light rays, so it cannot produce a parallel beam from a point source.
- **Option 3: Convex Mirror and Convex Lens**:
- A convex mirror diverges light rays, so it cannot produce a parallel beam from a point source.
- **Option 4: Perpendicular Plane to Plane Mirror**:
- A plane mirror reflects light but does not convert it into a parallel beam from a point source.

3. **Conclusion**:
- The only combination that can convert incident light from a point source into a parallel beam is **Concave Mirror and Convex Lens**.

### Final Answer:
The correct answer is **Concave Mirror and Convex Lens**.

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