A ray of light incident in water strikes the surface separating water from air making an angle of 10 ° with the normal to the surface. (refractive index of water = 1.3) a) What is the angle of refraction? b) What should be the angle of incidence if we want an angle of refraction not greater than 45 ° ? c) What is the critical angle?

Respuesta :

Answer:

a

 [tex]\theta _2 = 13^o[/tex]

b

 [tex]\theta _1 =32.94^o[/tex]

c

 [tex]\theta_c = 53.05^o[/tex]    

Explanation:

From the question we are told that

    The angle of incidence is  [tex]\theta_1 = 10^o[/tex]

    The refractive index of water is  [tex]n_1 = 1.3[/tex]

  Generally Snell's law is mathematically represented as

          [tex]n_1 sin(\theta_1) = n_2 sin(\theta_ 2)[/tex]

Here [tex]n_2[/tex] is the refractive index of air with value  [tex]n_2 = 1[/tex]

         [tex]\theta_2[/tex]  is the angle of refraction

So  

        [tex]\theta _2 = sin^{-1}[\frac{n_1 * sin(\theta _1)}{n_2} ][/tex]

=>     [tex]\theta _2 = sin^{-1}[\frac{1.3 * sin(10)}{1} ][/tex]

=>     [tex]\theta _2 = 13^o[/tex]

Given that the angle should not be greater than [tex]\theta _2 =45^o[/tex]  then the angle of incidence will be

       [tex]\theta _1 = sin^{-1}[\frac{n_2 * sin(\theta _2)}{n_1} ][/tex]

=>     [tex]\theta _1 = sin^{-1}[\frac{1 * sin(45)}{1.3} ][/tex]

=>     [tex]\theta _1 =32.94^o[/tex]

Generally for critical angle is mathematically represented as

        [tex]\theta_c = sin^{-1}[\frac{n_2}{n_1} ][/tex]

=>     [tex]\theta_c = sin^{-1}[\frac{1}{1.3} ][/tex]  

=>     [tex]\theta_c = 53.05^o[/tex]