Angle of incidence is the angle formed at the point of incidence between the incident ray and the normal. Angle of refraction is the angle formed between the refracted ray and the normal .
According to Snell's law,
Here, are indexes of incidence and refraction.
are angles of incidence and refraction.
Given:
On putting these values in the Snell's law, we get
This is a linear equation, the graph of a line. This function is in slope intercept form, y=mx+b . In this example the slope is =riserun=3=31 and the y -intercept is −2