When light strikes a medium at an angle less than the critical angle, what happens to the light?

When light strikes a medium at an angle less than the critical angle, what happens to the light?

• A. It is reflected
• B. It is refracted
• C. It is absorbed
• D. It passes through unchanged

Answer: (A)

The main idea is how light behaves at a boundary when the incidence angle is below the threshold for total internal reflection. At angles smaller than the critical angle, light is transmitted into the second medium and a portion of it is refracted, bending according to Snell’s law. The ray’s speed changes as it enters the new medium, causing this bend (toward or away from the normal depending on which medium is denser). Total internal reflection only happens when the incidence angle exceeds the critical angle, so light is not completely reflected in this case. It’s also not simply passing through unchanged or being absorbed.

The main idea is how light behaves at a boundary when the incidence angle is below the threshold for total internal reflection. At angles smaller than the critical angle, light is transmitted into the second medium and a portion of it is refracted, bending according to Snell’s law. The ray’s speed changes as it enters the new medium, causing this bend (toward or away from the normal depending on which medium is denser). Total internal reflection only happens when the incidence angle exceeds the critical angle, so light is not completely reflected in this case. It’s also not simply passing through unchanged or being absorbed.