A thin convex lens of focal length 5 cm and a thin concave lens of focal length 4 cm are combined together (without any gap) and this combination has magnification when an object is placed 10 cm before the convex lens. Keeping the positions of convex lens and object undisturbed a gap of 1 cm is introduced between the lenses by moving the concave lens away, which lead to a change in magnification of total lens system to . The value of is _____.
[NOTE: This question was DROPPED by NTA in the official answer key. No correct option is assigned.]
- A
Bonus Question (Tick option A for Bonus Marks)
- B
Bonus Question (Tick option A for Bonus Marks)
- C
Bonus Question (Tick option A for Bonus Marks)
- D
Bonus Question (Tick option A for Bonus Marks)
This question was dropped by NTA in the official answer key — no option is marked correct. There is an ambiguity or error in the problem statement (likely around the sign convention or the value of when a thin lens combination has overall negative focal length).
Per NTA policy, full marks are typically awarded to all candidates who attempted the question.
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