Rays of light get refracted while passing from air to glass because

Refraction is defined as the change in the direction of light as it passes from one transparent medium to another [4]. This phenomenon occurs fundamentally because the speed of light varies across different media [2]. When light travels from air into glass, its speed reduces significantly; for instance, while light travels at approximately 3.0 × 10⁸ m/s in air, it slows to about 2.0 × 10⁸ m/s in glass [3]. The refractive index of a medium is the ratio of the speed of light in a vacuum to its speed in that specific medium [2]. Because glass has a higher refractive index (typically 1.5) compared to air (approximately 1.0), light travels slower in glass [1]. This change in speed at the interface causes the light rays to bend, typically toward the normal when entering the denser glass medium [2].

Sources

1. [4] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > Activity 9.10 > p. 147
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > What you have learnt > p. 159
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > 9.3.2 The Refractive Index > p. 148
4. [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > QUESTIONS > p. 150