Advantages of cassegrain telescope is/are

Options

A. Free of chromatic aberration
B. High resolving power
C. Free of spherical aberration
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding the Cassegrain Telescope**: The Cassegrain telescope is a type of reflecting telescope that uses a combination of concave and convex mirrors to gather and focus light. This design allows for a compact structure while maintaining a long focal length.

2. **Chromatic Aberration**: One of the advantages of the Cassegrain telescope is that it does not suffer from chromatic aberration. Chromatic aberration occurs when different colors of light are focused at different points, leading to a blurred image. Since the Cassegrain telescope uses mirrors instead of lenses, this issue is eliminated.

3. **Spherical Aberration**: Similar to chromatic aberration, spherical aberration is also minimized in the Cassegrain design. Spherical aberration happens when light rays that strike the edges of a spherical mirror are focused at different points than those that strike near the center. The design of the Cassegrain telescope helps to reduce this effect, leading to clearer images.

4. **Resolving Power**: The resolving power of a telescope refers to its ability to distinguish between two closely spaced objects. The Cassegrain telescope has a high resolving power due to its large aperture and effective design, allowing it to produce sharp images of distant celestial objects.

5. **Conclusion**: Based on the advantages discussed, the Cassegrain telescope has the following benefits:
- No chromatic aberration
- No spherical aberration
- High resolving power

Thus, all three advantages are present in the Cassegrain telescope.

### Final Answer:
The advantages of the Cassegrain telescope are:
1. No chromatic aberration
2. No spherical aberration
3. High resolving power