A convex lens is immersed in water. Its focal length
A. Increases
B. Remains same
C. Becomes infinite
D. Decreases
Answer: Option A
Solution (By JKSSB Mock Tests)
Lens maker's formula: 1/f = (μ_lens/μ_medium - 1)(...). In water, relative refractive index reduces, so power decreases, focal length increases. Glass in water behaves less converging.
Explanation:
Myopia (nearsightedness): image formed before retina, corrected with concave lens. Hypermetropia: cannot see near objects. Presbyopia age-related. Cataract lens opacity.
Explanation:
Fission: heavy nucleus (e.g., U-235) splits into smaller nuclei plus neutrons and energy. Fusion: light nuclei combine (e.g., hydrogen to helium). Both release energy. Fission used in reactors and bombs.
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