What is the requirement for refraction?

What is the requirement for refraction?

• A. Oblique incidence
• B. Different speeds
• C. Oblique incidence and different speeds
• D. Normal incidence

Answer: (C)

Refraction is the bending of a light ray as it passes from one medium into another because its speed changes. The bend only happens when the ray meets the boundary at an angle; if it hits straight on, the path continues in a straight line even if the speeds differ. Likewise, if the speeds are the same in both media, even an oblique entry won’t produce a bend—the angles before and after remain equal. So, to get the actual shift in direction we need two things at once: the incidence must be oblique, and the two media must have different speeds for light. That combination is what causes the change in direction described by refraction.

Refraction is the bending of a light ray as it passes from one medium into another because its speed changes. The bend only happens when the ray meets the boundary at an angle; if it hits straight on, the path continues in a straight line even if the speeds differ. Likewise, if the speeds are the same in both media, even an oblique entry won’t produce a bend—the angles before and after remain equal.

So, to get the actual shift in direction we need two things at once: the incidence must be oblique, and the two media must have different speeds for light. That combination is what causes the change in direction described by refraction.