Understanding Refraction: The Bending of Light Across Different Media
Refraction is the bending of light rays as they transition between different media, such as air and water. This phenomenon occurs due to changes in the speed of light in various materials, resulting in light being slowed down by differing amounts. The angle at which light refracts depends on the refractive index of the media involved. For example, light bends towards the normal when entering a denser medium like glass from air, and this bending can lead to effects like the appearance of objects appearing shallower in water. Discover how everything from rainbows to magnifying glasses relies on the principles of refraction.
Understanding Refraction: The Bending of Light Across Different Media
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Presentation Transcript
Refraction • Although light travels in straight lines, it bends when it passes from one medium to another Medium (plural “media”) - the material that is being used or undergoing a process
Refraction Refraction = the bending of light rays as they pass between two different media
Refraction • Refraction occurs due to changes in the speed of light in different mediums • Different media slow down light by different amounts • The more that light slows down, the more the light is refracted
Refraction in Water • Light rays change direction at the surface of the water • The image of the chest appears to be more shallow than the actual chest
Speed of Light • In a vacuum: • However, it is impossible for light to move at this speed when particles get in the way… or
Refraction • The particles in a medium slow down the passage of light waves • Light only refracts at the boundary when it is entering or leaving a medium
or Index of Refraction Index of Refraction = the amount by which a transparent medium decreases the speed of light (since units cancel, a refractive index does not have any units)
= 3.00 x 108 m/s 1.91 x 108 m/s Given:Speed of light in glass = 1.91 x 108 m/sSpeed of light in vacuum = 3.00 x 108 m/s = 1.57 The refractive index is 1.57
1.33 = 3.00 x 108 m/sv Given:Refractive index in water = 1.33Speed of light in a vacuum = 3.00 x 108 m/s v = 2.26 x 108 m/s The speed of light in water is 2.26 x 108 m/s
How Light Refracts • The part of the light beam that hits the medium first will slow down first
Angle of Refraction • The angle of refraction is measured relative to the normal low refractive index (e.g. air) high refractive index (e.g. glass) • Light bends towards the normal
Angle of Refraction high refractive index (e.g. glass) low refractive index (e.g. air) • Light bends away from the normal
Dispersion • The amount of refraction is different for each colour • A single beam of whitelight can be split into a rainbow of colours • Dispersion = the refraction of white light into separate wavelengths (colours)
