What is the bending of waves as they pass from one medium to another due to a change in speed?

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

Answer: (C)

Refraction is the bending of waves as they pass from one medium to another due to a change in speed. At the boundary, the wave changes speed when it enters the new material, and that change in speed makes its path turn. If the wave slows down, it bends toward the line perpendicular to the boundary (the normal); if it speeds up, it bends away from the normal. This is why light looks bent when it enters water from air or why lenses can steer light to a focus. Absorption means the wave loses energy, not a change in direction, and diffraction is the bending of waves around edges or through openings, not simply due to a speed change at a boundary.