This document covers several key physics concepts related to light, including: 1) The law of reflection which states that the angle of incidence equals the angle of reflection. 2) The definition of real and virtual images, with virtual images unable to be projected onto a screen. 3) The rules of refraction regarding how light bends when slowing down or speeding up between mediums. 4) Total internal reflection, which occurs when light travels from an optically dense to less dense medium at an angle greater than the critical angle, causing all light to reflect inside the denser medium.

1. Physics P8
Light

3. Angle of incidence = Angle of reflection

4. Periscope

5. Position of Image – the image is as far
behind the mirror as the object is in
front

6. Lateral inversion

7. 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.

8. Refraction

9. 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

11. Real and apparent depth

13. Key terms:
medium
normal
intersect
incident ray
refracted ray
parallel
optical density

14. Semi-circular block

16. Visible Light

17. Prisms

19. Dispersion

20. 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)

22. 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.

25. Optical Fibres

28. Uses of optical fibres
• Communincations • Medecine