Refractive index, Physics

Refractive index:

The most important optical measurement for any transparent material is its refractive index (n). The refractive index is the ratio of the speed of light (c) in a vacuum to the speed of light in the medium:

The speed of light in a material is always slower than in a vacuum, so the refractive index is always greater than one in the optical part of the spectrum. Although light travels in straight lines through optical materials, something different happens at the surface. Light is bent as it passes through a surface where the refractive index changes. The amount of bending depends on the refractive indexes of the two materials and the angle at which the light strikes the surface between them.

The angle of incidence and refraction are measured not from the plane of the surfaces but from a line perpendicular to the surfaces. The relationship is known as "Snells Law", which is written; ni sin I = nr sin R, where ni and nr are the refractive indexes of the initial medium and the medium into which the light is refracted. I and R are the angles of incidence and refraction.


Snell's law indicates that refraction can't take place when the angle of incidence is too large. If the angle of incidence exceeds a critical angle, where the sine of the angle of refraction would equal one, light cannot get out of the medium. Instead the light undergoes total internal reflection and bounces back into the medium.

Figure  illustrates the law that the angle of incidence equals the angle of reflection. It is this phenomenon of total internal reflection that keeps light confined within a fibre optic.


Posted Date: 9/13/2012 8:44:46 AM | Location : United States

Related Discussions:- Refractive index, Assignment Help, Ask Question on Refractive index, Get Answer, Expert's Help, Refractive index Discussions

Write discussion on Refractive index
Your posts are moderated
Related Questions
A baton twirler throws a spinning baton directly upward. As it goes up and returns to the twirler's hand, the baton turns through four revolutions. Ignoring air resistance and assu

Radionuclide is appropriate when several radioactive elements are involved.Most clinical diagnostics procedures used photons of some type usually gamma rays. Gamma rays with energ

Field Lines A field line is a locus in which is described through a vector field and a beginning location within the field. Field lines are meaningful for visualizing vector f

Which of the subsequent represent the two kinds of basic (single-concept) electric potential problems?

Break a stick with inertia Secure a small stick 18 to 20 cm in length. If no other stick is available a lead pencil will do. Fold a newspaper and place it near the edge of a ta

For the magnetic circuit shown in Figure find the current I in the coil needed to produce a flux of 0.45mWb in the air gap. The silicon iron magnetic circuit has a uniform cros

Hexane is throttled from 18.15 bar, 507.6 K to 0.1 bar.  Determine the temperature at the exit and the entropy generation. Steam is cooled under constant pressure from 400 o C,

write all equationes of projectile motion used in calculation of vertical and horizontal motion

Radiography and depletion of Ozone layer: What is Radiography?  A. The method in which soft X-rays are used in medical diagnosis is called radiography. What are the uses

Nortan'sTheorem can be stated as follows: Any two-terminal active network having voltage source and resistances when viewed from its output terminals is equal to a constant-curren