Short answer
Reflection sends light back from a surface. Refraction occurs when light enters a different optical medium and changes speed, usually changing direction. A lake can reflect the sky while also refracting light from objects beneath the water. 1 2
Reflection returns light; refraction transmits it into another medium and can bend its path. Both may occur at one interface.
On this page
At a glance
Scroll to compare all columns →
| Question | Reflection | Refraction |
|---|---|---|
| Direction after boundary | Back into original medium | Into transmitted medium |
| Familiar example | Mirror image | Bent-looking straw in water |
| Can coexist at one surface? | Yes | Yes |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Reflection. Redirection of light back into the medium it came from at a surface or boundary. 1
Refraction. Change in light’s propagation direction as it travels into a region where its speed differs. 2
Key differences
The law of reflection relates incoming and outgoing angles on the same side of a boundary. Refraction follows light that crosses into a medium with a different refractive index. The mechanisms and paths differ even when one surface produces both. 1 2
How to tell them apart
Trace the ray: does it return to where it came from or pass into the other material? A visible image on polished glass is reflected; a shifted view through the glass involves refraction. 1 2
Where they overlap
Many real boundaries split incoming light into reflected and transmitted portions. Smooth and rough surfaces can reflect, while lenses deliberately use refraction. 1 2
Edge cases
At normal incidence, light may change speed on entering a new medium without an obvious direction change; refraction still describes transmission between media. Total internal reflection can prevent transmitted rays under suitable conditions. 1 2
Why the distinction exists
Optics distinguishes returning and transmitting paths to design mirrors, lenses, cameras and fiber-optic systems. 1 2
Common misconceptions
Refraction is not just a weak reflection. A transparent window can show both effects at once. 1 2
Examples
Sunlight glinting off a pond is reflection. A submerged stick appearing displaced when viewed from air is refraction. 1 2
Sources
Sources checked October 3, 2026.
- OpenStax — The Law of Reflection. Reflection.
- OpenStax — The Law of Refraction. Refraction.