. An astronomical telescope in normal adjustment receives light from a distant source S

the tube length is now decreased slightly, then

A: No image will be formed

B: A virtual image of S will be formed at a finite distance

C: A large, real image of S will be formed behind the eyepiece, far away from It

D: A small, teal image of S will be formed behind the eyepiece dose to It

Best Answer

Explanation

In an astronomical telescope, L = ƒ₀+ ƒ_e

When tube length is decreased, the image formed by the objective lens will lie between principal focus and optical centre of eye lens instead of lying at the focus of eye lens. Therefore, a virtual image will be formed at a finite distance from the eye lens.

A virtual image of S will be formed at a finite distance.

No image will be formed, A large, real image of S will be formed behind the eyepiece, far away from It, and A small, teal image of S will be formed behind the eyepiece dose to It are incorrect because of the astronomical telescope, L = ƒ₀+ ƒ_e.

Final Answer

Option B is correct, That is A virtual image of S will be formed at a finite distance.