1. Refraction

2. How a mirror creates an illusion

3. Refraction
Light waves traveling from one medium to another change speed and angle.
When traveling from a denser medium (water) to a less dense medium (air) the angle of the light bends away from the ‘normal’

4. Refraction
When the light enters into a denser medium from a less dense medium, the opposite occurs, and light is bent towards the ‘normal’ angle.

5. Refraction in a bi-convex lens
Why, then, does the light passing through this lens converge?

6. Light passing through a diverging lens
Why would light passing through a b-concave lens split apart?