Total internal reflection can occur only when light travels from
Correct answer: B. a denser to a less dense medium at an angle greater than the critical angle
- A. a less dense to a denser medium at any angle
- B. a denser to a less dense medium at an angle greater than the critical angle
- C. a vacuum into glass
- D. any medium at normal incidence
Explanation
Both conditions are needed: the second medium must be optically less dense, and the angle of incidence must exceed the critical angle, which is about 42 degrees for glass to air. This is the principle behind optical fibres, prismatic binoculars and the sparkle of a cut diamond. At normal incidence there is no refraction to suppress.
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About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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