What is the primary reason optical fibers are bent without losing light transmission efficiency?
**Critical angle** C satisfies sinC = n₂/n₁, n₁>n₂, n₂=1 for air, n₁=1.52 for glass gives sinC=1/1.52=0.6579, C≈41.1°, for water n=1.33 C=48.75°. Beyond C, total internal reflection occurs, all light reflected, no refracted ray, used in optical fibers and prisms. Optical fibers maintain light transmission when bent because the angle of incidence at the core-cladding interface remains greater than the critical angle, ensuring total internal reflection. This allows light to follow the bend without escaping into the cladding. Substituting values gives Due to sustained total internal reflection, which matches expected image position and magnification from mirror/lens formula 1/f = 1/v - 1/u (lens) or 1/f =
Ref: NCERT > Physics Book > Ray Optics > Total Internal Reflection and Critical Angle