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See also

Reflection of waves and scientific model

and Refraction of waves and scientific model

4. The coincidence of reflection and refraction of visible light rays at an interface

 

Ray analysis diagram for less dense to a more dense medium e.g. air => water, air => glass or air => transparent plastic (like perspex).

Light ray passing through an interface from air into water (same for glass or plastic rectangular prisms)

When an incident ray of light hits a water or glass surface at the sort of angle illustrated, most of the light passes through the air-water interface and refracted, but a little is reflected.

Ray 1 is a correct 'fainter' reflected light ray (angle of incidence = angle of reflection).

Ray 2 is an incorrect reflected ray (angle i does not equal angle r).

Ray 3 is an incorrect refracted ray (bends away from the 'normal').

Ray 4 is a correct refracted ray (on entering a more dense medium the ray is bends towards the 'normal', angle of incidence > angle of refraction).

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Ray analysis diagram for a more dense to a less dense medium e.g. glass => air, water => air, transparent plastic block (like perspex) => air

Light ray passing through an interface from water (same for glass or plastic rectangular prisms) out into air.

In the diagram an incident ray of light hits a transparent surface at the sort of angle illustrated, most of the light passes through the air-water interface and refracted, but a little is reflected.

Ray 1 is an incorrect refracted ray (bends towards the 'normal')

Ray 2 is the correct refracted ray (on entering a less dense medium, the ray bends away from the 'normal', angle of incidence < angle of refraction).

Ray 3 is an incorrect reflected ray (angle i does not equal angle r).

Ray 4 is the 'fainter' but correct reflected ray (angle of incidence = angle of reflection).

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Reflection in a silvered thick glass plane mirror

Rather more complex than you imagine, involving both reflection and refraction.

Ray line 1 represents an incident visible light ray in air.

Ray line 2 is the first refraction, bending towards the normal in a more dense medium (glass).

Ray line 3 is the reflected ray from the ray line 2 (angle of incidence = angle of reflection on the silvered surface).

Ray line 4 is the direct reflection of ray line 1 (no refraction involved).

Ray line 5 is the refraction of ray line 3 (refracted ray bends away from the 'normal' in a less dense medium).

INDEX notes: Visible light rays - reflection, refraction and diffraction

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Keywords, phrases and learning objectives for the behaviour of visible light rays

Be able to describe and explain the coincidence of reflection and refraction of visible light rays at an air-glass interface, air-water interface and an air-transparent plastic interface like perspex.

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INDEX notes: Visible light rays - reflection, refraction and diffraction