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NEET PHYSICSRAY OPTICS AND OPTICAL INSTRUMENTSEasy

Question

A biconvex lens has power PP. It is cut into two symmetrical halves by a plane containing the principal axis. The power of one part will be:

A

0

B

P2\frac{P}{2}

C

P4\frac{P}{4}

D

PP

Step-by-Step Solution

  1. Lens Maker's Formula: The power PP of a lens is given by P=1f=(μ−1)(1R1−1R2)P = \frac{1}{f} = (\mu - 1)\left(\frac{1}{R_1} - \frac{1}{R_2}\right).
  2. Analysis of the Cut: The lens is cut into two symmetrical halves by a plane containing the principal axis (a horizontal or longitudinal cut).
  3. Effect on Parameters:
  • The radius of curvature of the curved surfaces (R1R_1 and R2R_2) remains unchanged.
  • The refractive index (μ\mu) of the material remains unchanged.
  1. Conclusion: Since none of the factors determining the focal length change, the focal length ff and the power PP of each half remain the same as the original lens.
  • Note: If the lens were cut perpendicular to the principal axis, it would become two plano-convex lenses, and the power would become P/2P/2. However, here the cut is along the axis.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from RAY OPTICS AND OPTICAL INSTRUMENTS. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSRAY OPTICS AND OPTICAL INSTRUMENTSbiconvexsymmetricalhalvescontainingprincipal

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