refracted

Meaning: A refracted wave is the part that passes into a second medium with its direction bent. At the boundary the wave's speed changes while its frequency stays the same, so its wavelength changes too. At an angle, the speed change turns the path: into a larger n (slower light) the ray bends toward the normal, into a smaller n it bends away. Along the normal, there is no bend.

Equation: n₁ sin θ₁ = n₂ sin θ₂, where n = c/v is the index of refraction (unitless), c = 3.00 × 10⁸ m/s, v is the speed in the medium (m/s), and θ is the angle from the normal (degrees or rad).

On the MCAT: Expect ray diagrams with air, water, glass, lenses or prisms. You predict bending direction, compare speed or wavelength, or apply Snell's law. From higher n to lower n beyond the critical angle, sin θc = n₂/n₁, there is total internal reflection and no refracted ray. Violet bends more than red in a prism because n depends on wavelength.

Common confusion: Angles are measured from the normal, not the surface. Frequency does not change on refraction. Reflected light stays in the first medium and is not refracted.