The value of critical angle for glass is_______________?
Correct answer: A. 42°
- A. 42°
- B. 47°
- C. 52°
- D. 50°
Explanation
For ordinary glass surrounded by air, the critical angle is approximately 42°, obtained from sin C = 1/n, with glass refractive index about 1.5: sin C = 1/1.5, giving C approximately 42°. Students may choose 47° or 50° by confusing the critical angle with another angle of refraction or using an unsuitable refractive index.
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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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