The number of lenses in a terrestrial telescope is

Options

A. two
B. three
C. four
D. six

Explanation

To determine the number of lenses in a terrestrial telescope, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components of a Telescope**:
- A typical telescope consists of two main lenses: the objective lens and the eyepiece lens. The objective lens gathers light and forms an image, while the eyepiece lens magnifies this image for viewing.

2. **Identifying the Type of Telescope**:
- A terrestrial telescope is specifically designed for viewing objects on the ground. It is similar to an astronomical telescope but includes additional components to correct the orientation of the image.

3. **Identifying the Additional Lens**:
- In a terrestrial telescope, there is an additional lens known as the erecting lens. This lens is used to invert the image produced by the objective lens so that it appears upright when viewed through the eyepiece.

4. **Counting the Lenses**:
- Therefore, in a terrestrial telescope, we have:
- 1 Objective Lens
- 1 Eyepiece Lens
- 1 Erecting Lens
- This gives us a total of 3 lenses.

5. **Conclusion**:
- Thus, the total number of lenses in a terrestrial telescope is 3.

### Final Answer:
The number of lenses in a terrestrial telescope is **3**.

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