A ray of light strikes the midpoint of one face of an equiangular (60°–60°–60°) glass prism (n = 1.5) at an angle of incidence of 39.8°. (a) Trace the path of the light ray through the glass, and find the angles of incidence and refraction at each surface.

Respuesta :

Answer:

a

The path of light ray through the glass is shown on the first uploaded image

First surface:

Angle of  incidence is  [tex]i_1 = 39.0^o[/tex]

Angle of  refraction  is  [tex]r_1= 25.23^o[/tex]

Second surface:

Angle of  incidence is  [tex]i_2 = 34.77^o[/tex]

Angle of  refraction  is  [tex]r_2= 58.80^o[/tex]

b

Since the angle of incidence is equal to the angle of reflection

Then at the first surface the angle of reflection  is  [tex]R = 39.8^o[/tex]

And at the first surface the angle of reflection  is  [tex]R_2 = 34.77^o[/tex]

Explanation:

From the question we are told that

     The angle of incidence is [tex]i_1 = 39.0^o[/tex]

      The refractive index of the prism is [tex]n_{p} = 1.5[/tex]

      The angle of the prism is [tex]A = 60^o[/tex]

The path of light ray through the glass is shown on the first uploaded image

  For the first surface of the prism

        According to Snell's law

                 [tex]n_{air} sin( i_1) = n_{p} sin( r_1)[/tex]

The refractive index of air [tex]n_{air}[/tex]  has a constant value of  1

Now making  the angle of refraction at the first surface of the prism [tex]r_1[/tex] the subject

             [tex]r_1 = sin^{-1}[\frac{sin (i_1) }{n_{p}} ][/tex]

                [tex]= sin^{-1}[\frac{sin(39.8)}{1.5} ][/tex]

               [tex]r_1= 25.23^o[/tex]

  For the second  surface of the prism

 looking at the diagram on the first uploaded image the angle of incidence is mathematically evaluated  as

                    [tex]i_2 = A - r_1[/tex]

Substituting values

                    [tex]i_2 = 60 -25.23[/tex]

                         [tex]=34.77^o[/tex]

        According to Snell's law

                 [tex]n_{p} sin( i_2) = n_{air} sin( r_2)[/tex]

Now making  the angle of refraction at the second surface of the prism [tex]r_2[/tex] the subject

                [tex]r_2 = sin^{-1} [\frac{n_p sin(i_2)}{n_air} ][/tex]

Substituting values into the equation

                [tex]r_2 = sin^{-1} [\frac{1.5 * sin(34.77)}{1}][/tex]

               [tex]r_2 =58.8^o[/tex]