A lens which is thicker in the middle and thinner at the edges is called a ________ lens.

Options

A. convex
B. concave
C. cylindrical
D. none of these

Answer

To solve the question, "A lens which is thicker in the middle and thinner at the edges is called a ________ lens," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Lenses**:
- There are two main types of lenses: convex lenses and concave lenses.
- A convex lens is thicker in the middle and thinner at the edges, while a concave lens is thinner in the middle and thicker at the edges.

2. **Identify the Characteristics of a Convex Lens**:
- A convex lens converges light rays that are parallel to its principal axis.
- The shape of a convex lens is such that it bulges outward, making it thicker at the center.

3. **Identify the Characteristics of a Concave Lens**:
- A concave lens diverges light rays that are parallel to its principal axis.
- The shape of a concave lens is such that it curves inward, making it thinner at the center.

4. **Analyze the Question**:
- The question specifically asks for a lens that is "thicker in the middle and thinner at the edges."
- Based on the definitions and characteristics, this description matches that of a convex lens.

5. **Select the Correct Answer**:
- Therefore, the correct answer to the question is "convex lens."

### Final Answer:
A lens which is thicker in the middle and thinner at the edges is called a **convex lens**.

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