Which lens bulges out in the middle

Options

A. concave
B. plano-convex
C. convex
D. concavo-convex

Explanation

To solve the question "Which lens bulges out in the middle?" we can follow these steps:

### Step 1: Understand the Types of Lenses
There are different types of lenses, and they can be categorized based on their shape:
- **Concave Lens**: Thinner in the middle and thicker at the edges.
- **Convex Lens**: Thicker in the middle and thinner at the edges.
- **Plano-Convex Lens**: One flat side and one bulging side.
- **Concavo-Convex Lens**: One concave side and one convex side.

### Step 2: Analyze Each Option
1. **Concave Lens**: As mentioned, this lens is thinner in the middle, so it does not bulge out.
2. **Plano-Convex Lens**: This lens has one flat side and one bulging side, but it does not bulge out in the middle like a convex lens.
3. **Convex Lens**: This lens is thicker in the middle and bulges outward, making it the correct answer.
4. **Concavo-Convex Lens**: This lens has one side that is concave and one that is convex, but it does not bulge out in the middle like a convex lens.

### Step 3: Identify the Correct Answer
From the analysis, the lens that bulges out in the middle is the **Convex Lens**.

### Conclusion
The correct answer to the question "Which lens bulges out in the middle?" is the **Convex Lens**.

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