Critical angle is the angle of incidence in the denser medium for which the angle of refraction in the rarer medium is equal to:
Correct answer: D. 90˚
- A. 0˚
- B. Angle of incidence
- C. Twice the angle of incidence
- D. 90˚
Explanation
Option D is correct. A 90˚ angle of refraction implies that the ray of light doesn't enter the rarer medium. Option A is wrong because the angle is from the normal to the ray. Option B is wrong since that happens for total internal reflection for angles bigger than the critical angle. Option C could be right but only if the critical angle is 45˚.
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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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