Reflection It is the phenomenon of light propagating back into its source medium after focusing on a separation surface between two media.
Refraction It is the phenomenon of light passing from one medium to another.
During a reflection the frequency and propagation speed are conserved, while during refraction only the frequency is kept constant.
Reflection and regular refraction
It happens when, for example, a cylindrical beam of light hits a totally smooth or quiet surface, so the reflected and refracted beams will also be cylindrical, so the light rays will be parallel to each other.
Reflection and diffuse refraction
It happens when, for example, a cylindrical beam of light hits a rough or rough surface, causing the reflected and refracted rays of light to have a random direction throughout space.
Reflection and selective refraction
The white light we receive from the sun, or from fluorescent lamps, for example, is polychromatic, ie it is formed by more than one monochromatic light, in the case of the sun, the seven of the rainbow: red, orange, yellow, green , blue, indigo and violet.
Thus, an object when illuminated by white light "selects" in the solar spectrum the colors we see, and reflect them diffusely, and thus seen by us.
If a body is seen white, it is because it reflects all the colors of the solar spectrum.
If a body is seen red, for example, it absorbs all other colors in the spectrum, reflecting only red.
If a body is "seen" black, it is because it absorbs all the colors of the solar spectrum.
It's called light filter the normally acrylic piece that only lets one of the colors in the solar spectrum pass, ie a red filter, makes the only selectively refracted color red.
To know more…
It is very common to use light filters in astronomy to observe stars, since they have different colors, mainly according to their temperature and distance from Earth.