A coin in a beaker filled with water appears raised. This ph enomenon occurs because of the property of

The phenomenon where a coin in a water-filled beaker appears raised is due to the refraction of light. Refraction is the bending of light as it passes from one medium to another with a different optical density [t3]. When light rays travel from the water (a denser medium) into the air (a rarer medium), they bend away from the normal at the interface [t4][t7]. Our brains interpret light as traveling in straight lines; therefore, the refracted rays reaching the eye appear to originate from a point higher than the actual physical location of the coin [c1][t3]. This creates a virtual image at an 'apparent depth' that is shallower than the 'real depth' [t2][t4]. Similar effects are observed with pencils appearing bent in water or letters appearing raised under a glass slab [c2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > Activity 9.8 > p. 146
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > 9.3 REFRACTION OF LIGHT > p. 145