When light meets a boundary at an angle less than the critical angle, what optical effect occurs?

When light meets a boundary at an angle less than the critical angle, what optical effect occurs?

• A. Reflection
• B. Refraction
• C. Absorption
• D. Transmission without change

Answer: (A)

When light crosses from one medium into another with a different refractive index, its speed changes and the path bends. This bending is refraction, governed by Snell’s law. If the incidence angle is less than the critical angle, light does not stay in the same direction or stay at the boundary; it enters the second medium and is refracted, changing its direction. There can be some reflection at the boundary as well, but the primary effect at this angle is refraction. Absorption would mean the light’s energy is taken up by the material, which isn’t what this boundary scenario describes, and transmission without change would require equal refractive indices or no bending, which isn’t the case here.

When light crosses from one medium into another with a different refractive index, its speed changes and the path bends. This bending is refraction, governed by Snell’s law. If the incidence angle is less than the critical angle, light does not stay in the same direction or stay at the boundary; it enters the second medium and is refracted, changing its direction. There can be some reflection at the boundary as well, but the primary effect at this angle is refraction. Absorption would mean the light’s energy is taken up by the material, which isn’t what this boundary scenario describes, and transmission without change would require equal refractive indices or no bending, which isn’t the case here.