angle of incidence vs angle of reflection graph

In such a case, the refracted ray will be closer to the normal line than the incident ray is this is the FST rule of refraction. On the other hand, if a light wave passes from a medium in which it travels fast (relatively speaking) into a medium in which it travels slow, then the light wave will refract towards the normal. In such a case, the refracted ray will be farther from the normal line than the incident ray this is the SFA rule of refraction. In Lesson 1, we learned that if a light wave passes from a medium in which it travels slow (relatively speaking) into a medium in which it travels fast, then the light wave would refract away from the normal. Refraction is caused by the change in speed experienced by a wave when it changes medium. This phenomenon of total internal reflection has many practical applications in optics.Refraction is the bending of the path of a light wave as it passes across the boundary separating two media. Another characteristic of internal reflection is that there is always an angle of incidence q c above which all light is reflected back into the medium. This polarization by reflection is exploited in numerous optical devices.

The reflected light is then linearly polarized in a plane perpendicular to the incident plane. Note that the reflected amplitude for the light polarized parallel to the incident plane is zero for a specific angle called the Brewster angle. These curves are the graphical representation of the Fresnel equations. Internal reflection implies that the reflection is from an interface to a medium of lesser index of refraction, as from water to air. The illustration shows typical reflection curves for internal reflection.

Typical reflection and transmission curves for external reflection. Perpendicular case: Reflected % and transmitted %. Parallel case: Reflected % and transmitted %. Which applies to both the parallel and perpendicular cases. For further details, see Jenkins and White.Ĭhecking out conservation of energy in this situation leads to the relationship When you take the intensity times the area for both the reflected and refracted beams, the total energy flux must equal that in the incident beam. (For example, try light incident from a medium of n 1=1.5 upon a medium of n 2=1.0 with an angle of incidence of 30°.) But the square of the transmission coefficient gives the transmitted energy flux per unit area (intensity), and the area of the transmitted beam is smaller in the refracted beam than in the incident beam if the index of refraction is less than that of the incident medium. You can choose values of parameters which will give transmission coefficients greater than 1, and that would appear to violate conservation of energy. The signs of the coefficients depend on the original choices of field directions. Note that these coefficients are fractional amplitudes, and must be squared to get fractional intensities for reflection and transmission. For a dielectric medium where Snell's Law can be used to relate the incident and transmitted angles, Fresnel's Equations can be stated in terms of the angles of incidence and transmission.įresnel's equations give the reflection coefficients: That is, they give the reflection and transmission coefficients for waves parallel and perpendicular to the plane of incidence. Fresnell's Equations: Reflection and Transmission Fresnel's Equationsįresnel's equations describe the reflection and transmission of electromagnetic waves at an interface.

Angle of incidence vs angle of reflection graph