Match List-I with List-II
| List-I | List-II | ||
|---|---|---|---|
| Properties/Characteristics | Type of optical instrument | ||
| (A) | Gives maximum possible magnification \( \le 9 \) for realistic focal lengths. | (I) | Cassegrain Telescope |
| (B) | Objective - Small Aperture, Eyepiece - Large Aperture | (II) | Simple Microscope |
| (C) | Concave mirror is used as Objective | (III) | Refracting type telescope |
| (D) | Objective - Large Aperture, Eyepiece - Smaller Aperture | (IV) | Compound Microscope |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) - (II), (B) - (IV), (C) - (I), (D) - (III)
A microscope magnifies a nearby small object; a telescope collects light from a distant object.
(A) Gives maximum possible magnification \( \le 9 \) for realistic focal lengths. — this matches (II) Simple Microscope. With \( m = 1 + D/f \) and realistic focal lengths, \( m \) stays below about 9.
(B) Objective - Small Aperture, Eyepiece - Large Aperture — this matches (IV) Compound Microscope. Its objective is a small lens of very short focal length placed close to the object.
(C) Concave mirror is used as Objective — this matches (I) Cassegrain Telescope. It is a reflecting telescope with a concave-mirror objective.
(D) Objective - Large Aperture, Eyepiece - Smaller Aperture — this matches (III) Refracting type telescope. Its objective has a large aperture to gather light from a faint distant object.
Note: Item (D) describes every telescope, so it fits both the Cassegrain telescope (I), whose concave-mirror objective also has a large aperture, and the refracting telescope (III). The question can still be solved, because item (C) fits only (I), and Option (4) is the only option that matches (A) with (II), (B) with (IV) and (C) with (I).
NCERT (2026-27):
The Microscope – “… A simple microscope has a limited maximum magnification (≤ 9) for realistic focal lengths.”
Telescope – “… But here, the objective has a large focal length and a much larger aperture than the eyepiece.”
Telescope – “… For these reasons, modern telescopes use a concave mirror rather than a lens for the objective.”
Telescope – “… One such arrangement using a convex secondary mirror to focus the incident light, which now passes through a hole in the objective primary mirror, is shown in Fig. 9.26. This is known as a Cassegrain telescope, after its inventor.”