The convex lens of larger focal length used in a compound microscope is called

Options

A. objective
B. eye piece
C. erector lens.
D. None of these

Answer

To solve the question "The convex lens of larger focal length used in a compound microscope is called," we need to understand the components of a compound microscope.

### Step-by-Step Solution:

1. **Identify the Components of a Compound Microscope**:
A compound microscope typically consists of two main lenses: the objective lens and the eyepiece (or ocular lens).

2. **Understand the Function of Each Lens**:
- The **Objective Lens** is the lens closest to the object being observed. It has a shorter focal length and is responsible for forming a magnified image of the object.
- The **Eyepiece (or Eyepiece Lens)** is the lens through which the viewer looks. It has a longer focal length compared to the objective lens and is used to further magnify the image produced by the objective lens.

3. **Compare Focal Lengths**:
In a compound microscope, the eyepiece has a larger focal length than the objective lens. This is a key point in understanding the question.

4. **Evaluate the Given Options**:
- **Objective Lens**: This is incorrect as it has a shorter focal length.
- **Eyepiece**: This is correct as it has a larger focal length.
- **Erector Lens**: This is incorrect as it is not a standard component of a compound microscope.
- **None of These**: This is incorrect since we have identified the correct answer.

5. **Conclusion**:
Therefore, the convex lens of larger focal length used in a compound microscope is called the **Eyepiece**.

### Final Answer:
The convex lens of larger focal length used in a compound microscope is called the **Eyepiece**.

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