Home › NEET UG › Physics › Ray Optics and Optical Instruments › For light going from a medium of refractive inde…
For light going from a medium of refractive index n to air, the critical angle i_c is given by:
Asin i_c = n
Bsin i_c = 1/n
Ccos i_c = n
Dtan i_c = 1/n
Answer & Solution
Correct answer: B. sin i_c = 1/n
At the critical angle, r = 90°. Snell's law: **n × sin i_c = 1 × sin 90° = 1 → sin i_c = 1/n**. For water (n = 1.33): i_c ≈ 48.75°. For diamond (n = 2.42): i_c ≈ 24.4° (small i_c → strong TIR → diamond sparkle).
Related questions
The phenomenon by which the apparent position of a star near the horizon appears slightly An object is placed at the FOCUS of a concave mirror ($u = f$, both negative). The image fWhen light travels from one medium to another, which property of the wave REMAINS UNCHANGELight passing through a PRISM is dispersed because different colours of light haveA converging lens of focal length $20\,\text{cm}$ produces a real image at $30\,\text{cm}$Optical fibres use TOTAL INTERNAL REFLECTION to transmit light over long distances. The MATwo thin lenses of powers $+5\,\text{D}$ and $-3\,\text{D}$ are placed in CONTACT. The totThe POWER of a lens (in diopters, D) is defined as