What is the name of the formula used to calculate the angle of refraction within a material?

The formula used to calculate the angle of refraction when a wave passes from one medium to another is Snell's Law. This law describes how light or sound waves change direction as they move between different media with varying densities.

Snell's Law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant and is related to the velocities of the waves in the respective media. Mathematically, it is expressed as:

( n_1 \sin(\theta_1) = n_2 \sin(\theta_2) ),

where ( n_1 ) and ( n_2 ) are the refractive indices of the two media, and ( \theta_1 ) and ( \theta_2 ) are the angles of incidence and refraction, respectively.

This principle is essential in various applications within nondestructive testing, particularly in ultrasonic testing, where understanding wave propagation is critical for accurately detecting and characterizing defects in materials.