In Snell's law, sin refers to the sine trigonometric function. Specifically, it is the sine of the angle of incidence and the sine of the angle of reflection (or refraction).
Understanding 'sin' in Snell's Law
Snell's Law describes how light (or other waves) bends when passing from one medium to another. According to the provided reference:
Snell's Law states that the ratio of the sine of the angle of incidence to the sine of the angle of reflection is a constant.
This constant is related to the properties of the two media involved.
The Formula
The law is often expressed as:
sin(i) / sin(r) = constant
Where:
- i represents the angle of incidence (the angle between the incoming ray and the normal to the surface).
- r represents the angle of reflection or refraction (the angle between the outgoing ray and the normal).
The reference uses 'angle of reflection', but in the context of light passing through a boundary and bending, 'angle of refraction' is the more standard term. However, sticking strictly to the reference, 'r' denotes the angle involved in the second medium.
What is the Sine Function?
The sine function is a fundamental concept in trigonometry. For an angle in a right-angled triangle, the sine of the angle is defined as the ratio of the length of the opposite side to the length of the hypotenuse.
In Snell's law, we apply this function to the angles at which light interacts with the boundary between two different media.
Why Use 'sin'?
The relationship described by Snell's law, involving the ratio of sines, is a direct consequence of the wave nature of light and how its speed changes when moving from one medium to another. The constant ratio is known as the relative refractive index between the two media.
Key Takeaway: The 'sin' in Snell's Law is the mathematical sine function applied to the angles involved in light bending at a boundary, forming a fundamental ratio that remains constant for any given pair of media.
