RRB Group D 27 Nov 2025 Shift 1 Solved Paper

Concept:The apparent raising of letters under a glass slab is caused by the refraction of light when it passes from one medium to another.Explanation:When light travels from air into a thicker medium like glass, its speed decreases and it bends towards the normal.When it exits the glass slab back into air, it bends away from the normal.This bending of light rays changes the apparent position of the letters, making them appear raised above their actual location.The glass slab has a higher refractive index (about $1.5$) than air (about $1.0$).Snell's law ($n_1 \sin\theta_1 = n_2 \sin\theta_2$) governs the amount of bending.The shift in the perceived image is a direct result of refraction and not due to polarization, scattering, or total internal reflection.Polarization refers to the orientation of light waves; it does not shift object positions.Scattering spreads light in different directions (e.g., sky colour) and does not cause this effect.Total internal reflection occurs only when light attempts to move from a denser to a rarer medium at an angle larger than the critical angle, which is not the case here.Answer:Refraction of light