When a beam of light travleing in a rare medium is reflected from a denser medium it:
Correct answer: B. Undergoes a phase change of 180°
- A. Suffers no phase change
- B. Undergoes a phase change of 180°
- C. Undergoes a phase change of 270°
- D. Undergoes a phase change of 90°
Explanation
When light waves hit the boundary of a denser medium, some of it is transmitted/refracted and some is reflected. When a wave undergoes a reflection at a denser medium then its crest is reflected as a trough and vice versa. So its phase changes at 180 degrees or pi. Hence the correct option is B. The image given below is the summary of this concept:
This question appeared on the ETEA MDCAT 2005 paper, which you can sit online with every answer explained.
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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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