The document discusses properties of light including reflection, refraction, and Snell's Law of Refraction. Reflection is the bouncing back of light off surfaces, either specularly from smooth surfaces or diffusely from rough surfaces. Refraction is the bending of light caused by changes in medium, with light bending toward the normal when moving to a denser medium. Snell's Law describes the relationship between incident and refracted angles of light.

1. Light Waves
Never miss an opportunity to see
anything that is beautiful.

2. Properties of Light
1. Reflection
the bouncing back of light
Specular reflection –
smooth surface
Diffuse reflection –
rough surface

3. LAW OF REFLECTION
1. The incident ray, the reflected ray,
and the normal to the surface of the
mirror all lie in the same plane.
2. The angle of reflection is equal to the
angle of incidence.
Solve this!
• Two adjacent plane mirrors form a right
angle, as shown in the figure. A light ray is
incident upon one of the mirrors at an angle
of 30° to the normal. What is the angle at
which the light ray is reflected from the
other mirror?

4. Simulation Link
https://phet.colorado.edu/sims/html/bending-
light/latest/bending-light_en.html

5. Properties of Light
• Refraction
the bending of light caused
by the change in speed of
light when it encounters a
medium of different density
Dependent on the wavelength

6. REFRACTION
• Light travels from air to
water.
• the incident angle is greater
than the angle of refraction.
• light bends towards the
normal when traveling
from a less dense medium
to a higher density
medium.
*optical density

7. • What is the speed of
light in a crown glass?
n = 1.52
c = 3 x 108 m/s
v = 3 x 108 / 1.52
v= 2 x 108 m/s

8. Snell’s Law of Refraction

9. Snell’s Law of Refraction
A light beam in air hits a sheet of crown glass at an angle of 30°. At
what angle is the light beam refracted? (n air = 1.00, n cg=1.52)

12. Happiness can
be found even
in the darkest
of times if one
only
remembers to
turn on the
light.