Refraction occurs whenever there is oblique incidence and different propagation speeds between two media.

Refraction occurs whenever there is oblique incidence and different propagation speeds between two media.

• A. Sometimes
• B. Cannot determine
• C. False
• D. True

Answer: (D)

Refraction is the bending of a wave as it crosses a boundary due to a change in propagation speed. For this bending to occur, two conditions must be met: the incidence must be oblique, so the wave hits the boundary at an angle, and the two media must have different propagation speeds (different refractive indices). If the incidence is normal to the boundary, the ray continues straight even if speeds differ, and if the speeds are the same, there is no bending even with oblique incidence. So the statement is true because it correctly states when refraction happens: oblique incidence plus a change in propagation speed between media.

Refraction is the bending of a wave as it crosses a boundary due to a change in propagation speed. For this bending to occur, two conditions must be met: the incidence must be oblique, so the wave hits the boundary at an angle, and the two media must have different propagation speeds (different refractive indices). If the incidence is normal to the boundary, the ray continues straight even if speeds differ, and if the speeds are the same, there is no bending even with oblique incidence. So the statement is true because it correctly states when refraction happens: oblique incidence plus a change in propagation speed between media.