http://www.ck12.org Chapter 20. Geometric Optics
20.5 Summary
- The Law of Reflection states that the angle of incidence is equal to the angle of reflectionθi=θr.
The incident ray, the reflected ray, and the normal are also coplanar.
- For the object distance,dothe image distancedi, and the focal lengthf, both the mirror equation and thin lens
equation isd^1 o+d^1 i=^1 f. - For spherical mirrors,f=r 2.
- The lateral magnificationmof an object is defined as the ratio of the image heighthiof the object to the actual
heighthoof the object. It is equal to the negative of the ratio of the image distancedito the object distancedo.
m=hhoi=−ddoi
- We define the ratio of the speed of light through vacuumcto the speed of the light through a particular mediumv
as the index of refractionn:
n=cv
Sincec>v, the index of refraction is always greater than 1 when traveling through any medium other than vacuum.
- Snell’s Law can be defined in terms of the indices of refractionn, or the speeds of light in the two media. It
expresses the relationship between the angle of incidenceθ 1 and the angle of refractionθ 2 at the interface of two
media.
n 1 sinθ 1 =n 2 sinθ 2
The index of refractionn 1 is the medium from which light originates andn 2 is the index of refraction of the medium
to which light passes. Angleθ 1 is measured with respect to the normal at the interface of the first medium and
angleθ 2 is measured with respect to the (same) normal at the interface of the second medium. Snell’s Law can be
expressed in terms of the velocities of light in the respective media as,
v 2 sinθ 1 =v 1 sinθ 2 ,
wherev 1 is the speed of the light in the first medium, andv 2 is the speed of light in the second medium.
- The law of reflection states that the angle of incidence is equal to the angle of reflectionθi=θr
The incident ray, the reflected ray and the normal are also coplanar.
- For the object distance,dothe image distancedi, and the focal lengthf, both the mirror equation and thin lens
equation isd^1 o+d^1 i=^1 f - For spherical mirrors,f=r 2
- The lateral magnificationmof an object is defined as the ratio of the image heighthiof the object to the actual
heighthoof the object, and is equal to the negative of the ratio of the image distancedito the object distancedo
m=hhoi=−ddoi
- We define the ratio of the speed of light through vacuumcto the speed of the light through a particular mediumv
as the index of refractionn
n=cv
Sincec>v, the index of refraction is always greater than 1 when traveling through any medium other than vacuum.
- Snell’s law can be defined in terms of the indices of refractionnor the speeds of light in the two media. It
expresses the relationship between the angle of incidenceθ 1 and the angle of refractionθ 2 at the interface of two