Match List I with List II
| LIST I | LIST II | ||
|---|---|---|---|
| A. | Power of concave lens | I. | Concave lens |
| B. | Power gets algebraically added | II. | Refraction of light |
| C. | Image formation by lens | III. | Negative |
| D. | Always virtual image | IV. | combination of lenses |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-III, B-IV, C-II, D-I
The power of a lens is \( P = 1/f \) (f in metres), with the sign of the focal length.
(A) Power of concave lens — this matches (III) Negative. A concave (diverging) lens has a negative focal length, so its power is negative.
(B) Power gets algebraically added — this matches (IV) combination of lenses. For thin lenses in contact, \( P = P_1 + P_2 + \ldots \), signs included.
(C) Image formation by lens — this matches (II) Refraction of light. A lens bends light by refraction at its two surfaces.
(D) Always virtual image — this matches (I) Concave lens. For a real object a concave lens always forms a virtual, erect and diminished image.
NCERT (2026-27):
Power of a Lens – “… Power of a lens is positive for a converging lens and negative for a diverging lens.”
Combination of Thin Lenses in Contact – “… Note that the sum in Eq. (9.32) is an algebraic sum of individual powers, so some of the terms on the right side may be positive (for convex lenses) and some negative (for concave lenses).”