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IGCSE Physics Light presentation
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Physics P8
Light
Angle of incidence = Angle of reflection
Periscope
Position of Image – the image is as far behind the mirror as the object is in front
Lateral inversion
Real and Virtual Images
The image being reflected in the first diagram above is a virtual image. When looking at a mirror image, the light rays that reflect off the mirror into your eye appear to come from the image. This virtual image cannot be projected onto a screen like at the cinema, unlike a real image. A real image can because it is formed by focusing light rays onto a screen.
Refraction
Rules for refraction
• Ray of light bends towards the normal when it slows down
• Ray of light bends away from the normal when it speeds up
• A ray of light travelling along the normal is not refracted
Real and apparent depth
Key terms:mediumnormalintersectincident rayrefracted rayparalleloptical density
Semi-circular block
Visible Light
Prisms
Dispersion
Total Internal Reflection• https://www.cdli.ca/courses/phys2204/unit04
_org02_ilo11/b_activity.html
• This is caused by refraction of rays from an optically dense medium to an optically less dense medium (e.g. glass to air)
Critical Angle
• At the critical angle (cº) the angle of refraction is 90º
• If the angle of incidence is greater than the critical angle, all of the light is reflected inside the denser medium.
• The light shows total internal reflection.
Optical Fibres
Uses of optical fibres
• Communincations • Medecine
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