The bending of a wave as it passes from one medium to another at an angle is known as

• A. Reflection
• B. Diffraction
• C. Interference
• D. Refraction

Answer: (D)

Refraction is the bending of a wave when it passes from one medium into another at an angle. This happens because the wave travels at different speeds in the two media, so the part of the wavefront that enters the new medium first changes speed while the rest is still in the old medium. That change in speed tilts the wave’s path, making the direction change as it crosses the boundary. For light, when entering a slower medium, the ray bends toward the normal (the line perpendicular to the boundary); when entering a faster medium, it bends away from the normal. The bending magnitude is described by Snell’s law, which relates the angles to the refractive indices of the two media. Other phenomena have different behaviors: reflection is the wave bouncing off the boundary, diffraction is bending around edges or through openings, and interference is the combination of waves producing a new pattern.