Consider the following statements
(A) Corpuscular model predicted that if the ray of light bends towards the normal after refraction then the speed of light would be greater in the second medium.
(B) In optical fibre, the refractive index of the core is kept higher than cladding.
(C) Diffraction due to clouds is efficient in equal measures for all wavelengths.
(D) Light travels faster in glass than in air.
(E) When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of \( \pi \).
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B) and (E) Only
(A) Corpuscular model predicted that if the ray of light bends towards the normal after refraction then the speed of light would be greater in the second medium. — Correct. In Newton's corpuscular model the surface pulls the corpuscles into the denser medium and increases their speed; the wave model and experiment show the opposite.
(B) In optical fibre, the refractive index of the core is kept higher than cladding. — Correct. Total internal reflection needs light going from a denser to a rarer medium, so the core must have the higher refractive index.
(C) Diffraction due to clouds is efficient in equal measures for all wavelengths. — Incorrect. Clouds look white because their large droplets scatter all wavelengths about equally; diffraction depends on the wavelength.
(D) Light travels faster in glass than in air. — Incorrect. Glass is optically denser, so light is slower in glass (\( v = c/n \)).
(E) When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of \( \pi \). — Correct. On reflection at the surface of a denser medium (light in air reflected by glass), the reflected wave undergoes a phase change of \( \pi \).
NCERT (2026-27):
Introduction – “… The corpuscular model predicted that if the ray of light (on refraction) bends towards the normal then the speed of light would be greater in the second medium.”
Total Internal Reflection in Nature and Its Technological Applications – “… Each fibre consists of a core and cladding. The refractive index of the material of the core is higher than that of the cladding.”