What causes a light ray to bend when entering a different medium?

What causes a light ray to bend when entering a different medium?

• A. The light's color
• B. A change in light speed as it enters a new medium
• C. The surface roughness
• D. The wavelength remains constant

Answer: (B)

Light bends when entering a different medium because its speed changes. Light travels at different speeds in air, water, glass, and so on; when the ray hits the boundary at an angle, the part of the light that enters the new medium must slow down (or speed up) while the part in the original medium remains at its previous speed. This difference in speed across the boundary makes the path change direction, which is refraction. The color of light isn’t what makes it bend, and surface roughness would scatter light rather than produce a clean bend. Also, the wavelength does not stay the same in a new medium—it changes because the light speed changes. The core idea is that the bend comes from a change in speed as light crosses into a different material.

Light bends when entering a different medium because its speed changes. Light travels at different speeds in air, water, glass, and so on; when the ray hits the boundary at an angle, the part of the light that enters the new medium must slow down (or speed up) while the part in the original medium remains at its previous speed. This difference in speed across the boundary makes the path change direction, which is refraction. The color of light isn’t what makes it bend, and surface roughness would scatter light rather than produce a clean bend. Also, the wavelength does not stay the same in a new medium—it changes because the light speed changes. The core idea is that the bend comes from a change in speed as light crosses into a different material.