Question 12 — Place a pencil behind - Questions at the end of the chapter - Chapter 10 Class 8 - Light: Mirrors and Lenses (Curiosity)

Last updated at June 17, 2026 by

Q 12
Question

Place a pencil behind a transparent glass tumbler. Now fill the tumbler halfway with water. How does the pencil appear when viewed through the water? Explain why its shape appears changed.

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Answer
The water-filled tumbler acts like a convex lens.

Explanation

  • The curved tumbler full of water bulges in the middle.
  • So it acts like a convex lens.
  • It bends the light coming from the pencil.
  • The pencil looks wider, shifted, or appears to bend at the water line.
The water and curved glass form a convex lens that bends light, so the pencil looks changed.
← Back to concept: 10.4 What Is a Lens?
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