The refractive index of a medium is defined as
Correct answer: B. the speed of light in a vacuum divided by the speed in the medium
- A. the speed of light in the medium divided by the speed in a vacuum
- B. the speed of light in a vacuum divided by the speed in the medium
- C. the angle of incidence divided by the angle of refraction
- D. the wavelength in the medium divided by that in a vacuum
Explanation
Since light always travels slower in a material than in a vacuum, the refractive index is always greater than one, being about 1.33 for water and 1.5 for glass. Snell's law relates the sines of the angles, not the angles themselves, which is the trap in the third option. The frequency stays the same on refraction while the wavelength shortens.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
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.
Practise Optics
665 free Optics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 11 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Optics questions
Light travelling from a denser medium into a less dense one bends
What is the approximate speed of light in a vacuum?
Total internal reflection can occur only when light travels from
An optical fibre transmits light along its length by
A converging lens forms a real, inverted and magnified image when the object is placed
The power of a lens is measured in dioptres and is equal to