When refractive index of lens is equal to the refractive index of liquid, the lens behave like a plane surface with focal length infinity.
NEET UG 2003 — Physics Optics
A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will:
Held on 30 Apr 2003 · Verified 9 Jul 2026.
become zero
become infinite
become small, but non-zero
remain unchanged
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