Understanding the Concepts
* Refraction: When light travels from one medium to another (like water to air), it changes direction. This bending of light is called refraction.
* Angle of Incidence: The angle between the incoming light ray and the normal (a line perpendicular to the surface) is the angle of incidence.
* Angle of Refraction: The angle between the refracted light ray and the normal is the angle of refraction.
* Snell's Law: This law mathematically describes the relationship between the angle of incidence, angle of refraction, and the indices of refraction of the two mediums.
The Scenario: Water to Air
* Water's Index of Refraction (n1): Approximately 1.33
* Air's Index of Refraction (n2): Approximately 1.00
When light travels from a denser medium (water, higher index of refraction) to a less dense medium (air, lower index of refraction), it bends *away* from the normal.
Calculating the Angle of Refraction
Using Snell's Law:
n1 * sin(angle of incidence) = n2 * sin(angle of refraction)
1.33 * sin(15°) = 1.00 * sin(angle of refraction)
Solving for the angle of refraction:
angle of refraction = arcsin(1.33 * sin(15°) / 1.00) ≈ 20.2°
In Summary
When a light ray enters air from water at a 15-degree angle to the normal:
* It will bend away from the normal.
* The angle of refraction will be approximately 20.2°.
Important Note: This calculation assumes the light is entering the air from the water. If the light is traveling from air to water, the angle of refraction will be smaller than the angle of incidence, and the light will bend towards the normal.
