Neco Model Questions Vol1 2025 Physics Question 19

Practice objective / multiple choice question 19 from the 2025 Neco Model Questions Vol1 Physics examination.

Neco Model Questions Vol1 2025 Physics Objective / Multiple Choice Hard Difficulty
Question 19 NECO_MODEL_QUESTIONS_VOL1 • 2025 • PHYSICS • objective

A biconvex lens is made of glass with refractive index \(n_{\text{glass}}=1.50\). Its radii of curvature are \(R_{1}=+15\ \text{cm}\) and \(R_{2}=-20\ \text{cm}\) (sign convention: convex surface facing the object is positive). (i) When the lens is immersed in water (\(n_{\text{water}}=1.33\)), determine its focal length in water. (ii) When the same lens is used in air, find its focal length in air, and then determine the image distance and magnification for an object placed \(40\ \text{cm}\) from the lens in air.

Answer Options

Correct Answer A. f_water ≈ 67 cm; f_air ≈ 17.1 cm; image distance v ≈ 30 cm; magnification m = -0.75
B. f_water ≈ 72 cm; f_air ≈ 18.3 cm; image distance v ≈ 32 cm; magnification m = -0.80
C. f_water ≈ 55 cm; f_air ≈ 14.0 cm; image distance v ≈ 26 cm; magnification m = -0.65
D. f_water ≈ 60 cm; f_air ≈ 15.5 cm; image distance v ≈ 28 cm; magnification m = -0.70
Correct Answer
A
Correct Option:
f_water ≈ 67 cm; f_air ≈ 17.1 cm; image distance v ≈ 30 cm; magnification m = -0.75

About This Question

This is Neco Model Questions Vol1 2025 Physics Question 19. It is one of the objective questions from the 2025 Neco Model Questions Vol1 Physics examination.

Difficulty level: Hard .

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