Light Reflection and Refraction

Light Reflection

• Light reflection is the change in direction of a light ray when it hits a surface.
• The angle of incidence is equal to the angle of reflection (governed by the law of reflection).
• Reflection can be specular (smooth surfaces, like mirrors) or diffuse (rough surfaces).
• Specular reflection produces clear images, while diffuse reflection scatters light in many directions.
• Examples include seeing your reflection in a mirror or light bouncing off a wall.

Light Refraction

• Light refraction is the bending of light as it passes from one medium to another with a different density.
• The change in speed of light causes the change in direction.
• Denser mediums cause light to slow down and bend towards the normal (an imaginary line perpendicular to the surface).
• Less dense mediums cause light to speed up and bend away from the normal.
• Examples include a straw appearing bent in a glass of water, or the twinkling of stars.
• Refraction is crucial for lenses in eyeglasses, cameras, and telescopes.

Light Dispersion

• Light dispersion is the separation of white light into its constituent colors (red, orange, yellow, green, blue, indigo, violet).
• This occurs because different colours of light have different wavelengths and refract at different angles when passing through a prism or other transparent medium.
• Red light refracts the least, violet the most.
• The degree of refraction depends on the wavelength of light.
• The phenomenon is responsible for rainbows and the colours we see in a prism.

Colours of Light

• Visible light is a small part of the electromagnetic spectrum.
• Colours are perceived due to the different wavelengths of light.
• Red has the longest wavelength, violet the shortest.
• Different combinations of wavelengths result in different colours.
• Mixing colours of light is additive; mixing paints (pigments) is subtractive, creating different effects.
• White light is the combination of all colours of the visible spectrum.
• Black is the absence of visible light.
• Complementary colours are colours that produce white light when mixed together (e.g., red and cyan).
• Subtractive colour mixing is crucial in painting, printing, and other visual arts.
• Mixing colours of pigment (e.g. paints) removes wavelengths of light, producing new shades.
• Additive color mixing is important for light-emitting sources and computer monitors and televisions.
• Adding different wavelengths of light creates more complex colours.
• Our perception of colour is influenced by many factors, like lighting conditions and individual interpretation.