As a wave travels into and through a different transmission medium, the wave's direction, speed, and wavelength are altered. What is this phenomenon called?

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

Answer: (B)

Refraction is the change in direction, speed, and wavelength a wave experiences as it crosses into a different medium. When the wave enters the new material, its speed changes due to the medium’s properties. Since the frequency stays the same across the boundary, the wavelength must adjust to match the new speed. Parts of the wavefront that hit the boundary at different angles will travel at different speeds in the new medium, causing the wave to bend. This bending follows Snell’s law, relating the incidence and refraction angles to the speeds (or refractive indices) of the two media. For example, light slows down and bends toward the normal when entering a denser medium like water from air. The other terms describe different phenomena: reflection is bouncing off the boundary, diffraction is bending around obstacles or through openings, and scattering involves redirection by particles in a medium.