# P1.1 - Reflection and Refraction

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• P1.1 - Reflection and Refraction
• Light travels as waves, normally in straight lines unless it is reflected or refracted
• Reflection
• Reflection is a chnge in direction of a wave upon striking the interface between two materials
• Diagram
• Incident ray - ray or light that strikes a surface
• Refraction
• Light slows down when entering a denser object
• E.g: air and glass
• Causes the light to change direction
• Light bends towards to normal when entering denser material
• Angle of refraction - the angle made by a refracted ray with the normal
• Diagram
• There is slight reflection at points where the density changes (glass block)
• When a ray enters a denser medium it bends toward the normal
• When entering a less dense object, the rays bends away from the normal
• Normal - line perpendicular to surface
• Refraction
• Light slows down when entering a denser object
• E.g: air and glass
• Causes the light to change direction
• Light bends towards to normal when entering denser material
• Angle of refraction - the angle made by a refracted ray with the normal
• Diagram
• There is slight reflection at points where the density changes (glass block)
• When a ray enters a denser medium it bends toward the normal
• When entering a less dense object, the rays bends away from the normal
• Angle of Reflection - the angle made by a reflected ray with the normal
• Angle of reflection = angle of incidence
• Finding the focal langth
• Diagram
• How to find the focal point of a lens
• Use lens to focus parallel rays of light from distant object onto a screen/piece of paper
• Rays of light will meet at paper to form a real, inverted image.
• Move lens until image is focused
• The focal length is the distance between lens and paper
• The focal point is the point where all the parallel rays are brought together
• Lenses
• Converging lenses makes rays of light come together
• A converging lens can be used as a magnifying glass if it is held close to an object
• This produces a virtual image because the rays of light only appear to be coming from it
• It is also magnified and the right way up
• The fatter the lense the shorter the focal point
• The magnification of an image depends on:
• Focal length
• Distance between object and lens