Question

A beam of monochromatic light goes from material 1 with index of refraction n1 into material 2 with index of refraction n2. the frequency of light in material 1 is f1 and in material 2 is f2. what is the ratio of f1/f2?

Answer 1

To solve this problem, we should remember that the formula for index of refraction is defined as:

n = c / v

or

n v = c

Where,

n = index of refraction

c = speed of light

v = speed of light in the medium

Since speed of light is constant, then we can simply equate the materials 1 and 2:

n1 v1 = n2 v2

Where the speed of light in the medium (v) can be expressed as:

v = w * f

Where,

w = wavelength of light

f = frequency of light

Therefore substituting this back into the relating equation:

n1  w1 f1 = n1  w2 f1

Since it is given that the light is monochromatic, w1 = w2, this further simplifies the equation to:

n1 f1 = n2 f2

f1 / f2 = n2 / n1                  (ANSWER)