Snell's Law Calculator
Calculate refraction angles and detect total internal reflection.
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Enter the refractive indices of both media and the angle of incidence in degrees. The calculator shows the refracted angle, critical angle (if applicable), and whether total internal reflection occurs.
About Snell's Law
Snell's law, named after Willebrord Snellius, governs the refraction of light at the boundary between two media. When light enters a denser medium, it bends toward the normal; when entering a less dense medium, it bends away. If the angle of incidence exceeds the critical angle when going from denser to less dense, total internal reflection occurs. This principle is essential for designing lenses, optical fibers, prisms, and understanding rainbows.
Frequently Asked Questions
What is Snell's law?
Snell's law describes how light bends when passing from one medium to another: n1 sin(theta1) = n2 sin(theta2). Light bends toward the normal when entering a denser medium.
What is total internal reflection?
When light travels from a denser to a less dense medium at an angle greater than the critical angle, it is completely reflected back. This is the principle behind fiber optics and prisms.
What is the critical angle?
The critical angle is the angle of incidence above which total internal reflection occurs. It equals arcsin(n2/n1) and only exists when n1 is greater than n2.