Question

The final image formed by a terrestrial telescope is

• A. virtual and inverted compared to the object
• B. virtual and erect compared to the object
• C. real and erect compared to the object
• D. none of these

Hint:

The name of the telescope gives a clue to the image orientation. "Terrestrial" relates to Earth. When you look at things on Earth (like a ship or a building), you want to see them the right way up. Therefore, a terrestrial telescope must produce an erect (upright) final image.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
A terrestrial telescope is designed for viewing objects on Earth. A key requirement for this purpose is that the final image must be upright (erect) relative to the object. This distinguishes it from an astronomical telescope, where an inverted image is acceptable.
Step 2: Detailed Explanation:
A terrestrial telescope typically consists of three main components:
1. Objective Lens: This is a convex lens that gathers light from a distant object and forms a real, inverted, and diminished image at its focal plane.
2. Erecting System: To make the final image upright, an additional lens or prism system is placed between the objective and the eyepiece. A common method uses a single convex lens called the erecting lens. This lens takes the real, inverted image from the objective and forms a second image that is real, and now erect.
3. Eyepiece: This is another convex lens that acts as a simple magnifier. The observer looks through the eyepiece at the real, erect image formed by the erecting system. The eyepiece forms a final, magnified image that is virtual and remains erect.
Therefore, the final image seen by the observer is magnified, virtual, and erect with respect to the original object.
Step 3: Final Answer:
The final image formed by a terrestrial telescope is virtual and erect. Hence, option (B) is the correct answer.