Applications of Fresnel Equations for Light Intensities

ratio of parallel light to total light:

I

p

/ I

0.5

upper refractive index:

n

1

1

lower refractive index:

n

2

1.5

φ

0

=

π

4

rad. = 45° 0' 0''

φ

1

= 0.490883 rad. = 28° 7' 31.8205''

Brewster's angle = 0.982794 rad. = 56° 18' 35.7569''

r

s

=

E

r

s

E

i

s

= 0.303337

t

s

=

E

t

s

E

i

s

= 0.696663

r

p

=

E

r

p

E

i

p

= 0.0920134

t

p

=

E

t

p

E

i

p

= 0.728009

This Demonstration shows the change of light intensity when light passes between two dielectric media, making use of the Fresnel equations.

The red light beam (

s

) represents the light perpendicular to the plane of incidence; the yellow light beam (

p

) shows the light parallel to the plane of incidence.

Using the slider, you can change the intensity ratio of the light parallel to the plane of incidence to the total intensity. This will also show the blend of the two colors representing the mixture of lights in the two directions. As light is transmitted and reflected, the intensities of both beams change, which is indicated by the opacity of the two colors.