Which statement about light at a boundary is correct?

Which statement about light at a boundary is correct?

• A. Only reflection occurs at the boundary.
• B. Only refraction occurs at the boundary.
• C. Diffraction occurs at the boundary.
• D. Both reflection and refraction can occur at the boundary.

Answer: (D)

When light meets the boundary between two materials, it behaves as a wave that can do two things at once: part of it reflects back into the first material, and part of it transmits into the second material and changes direction. The reflected ray follows the rule that the angle of incidence equals the angle of reflection. The transmitted (refracted) ray changes direction according to Snell’s law, because its speed is different in the second medium. Because of this, both reflection and refraction can occur at the boundary. Diffraction is a separate wave effect that happens when light bends around edges or through openings, not the main behavior at a smooth boundary. So the statement that both reflection and refraction can occur is the correct one.

When light meets the boundary between two materials, it behaves as a wave that can do two things at once: part of it reflects back into the first material, and part of it transmits into the second material and changes direction. The reflected ray follows the rule that the angle of incidence equals the angle of reflection. The transmitted (refracted) ray changes direction according to Snell’s law, because its speed is different in the second medium. Because of this, both reflection and refraction can occur at the boundary. Diffraction is a separate wave effect that happens when light bends around edges or through openings, not the main behavior at a smooth boundary. So the statement that both reflection and refraction can occur is the correct one.