2. Lenses and Mirrors
Mrs. Gergel

3. Refraction
When light rays enter a new medium at an angle the change in speed causes them to bend, or change direction
It travels fastest in air and slowest through glass. Glass causes light to bend more than either air or water because glass refracts light more
Index or refraction- a measure of how much a ray of light bends when it enters new material
The higher the index refraction of a medium the more it bends light

4. Prisms and Rainbows
When white light enters a prism each wavelength is refracted by a different amount
When white light from the sun shines through tiny drops of water, a rainbow may appear
Raindrops act like tiny prisms, refracting and reflecting light and separating colors
Colors of the rainbow always appear in the same order because raindrops refract the shorter wavelengths the most

5. Mirages
A mirage is an image of a distant object caused by refraction of light

6. Lenses
Lens is a curved piece of glass or other transparent material that is used to refract light
A lens forms an image by refracting light rays that pass through it
Lenses have different shapes
Convex
Concave
The type of image formed by a lens depends on the shape of the lens

7. Concave Lenses
A concave lens is thinner in the center than at the edges
As parallel rays of light pass through a concave lens, they are bent away from the center of the lens
Because the light rays never meet, a concave lens can produce only a virtual image

8. Virtual Image Virtual image- are right side up, or upright
We see virtual images because brain assumes that light travels in a straight line. The brain treats the light rays as though they were coming from behind the mirror instead of being reflected

9. Convex Lenses Convex lens is thicker in the center than at the edges
As parallel light rays pass through a convex lens, they are bent toward the center of the lens
Rays meet at the focal point of the lens and then continue on
The more curved the lens, the more it refracts light
The type of image formed by a convex lens depends on the position of the object in relation to the focal point. It may be a virtual image or a real image.

10. Real Image
If the object is farther away from the mirror/lens than the focal point, the reflected rays form a real image
Real image is formed when rays actually meet at a point
Real images are upside down or inverted
A real image may be larger or smaller than the object

11. Mirrors
A mirror is a sheet of glass that has a smooth, silver-colored coating on one side. When light passes through the glass, the coating on the back reflects the light regularly, allowing you to see an image
An image is a copy of an object formed by reflected or refracted rays of light
Mirrors can be flat or curved
The shape of the surface determines how the image will look

12. Plane Mirrors
Plane mirror- a flat mirror that produces an upright virtual image the same size as the object
The image you see in a plane mirror is a virtual image
Virtual image- are right side up, or upright
We see virtual images because brain assumes that light travels in a straight line. The brain treats the light rays as though they were coming from behind the mirror instead of being reflected

13. Concave Mirror
A mirror with a surface that curves inward like the inside of a bowl is a concave mirror
Focal point is the point at which the rays meet
Concave mirrors can form either virtual images or real images
The type of image depends on the position of the object in relation to the focal point

14. Convex Mirror
A mirror with a surface that curves outward is called a convex mirror
The focal point of a convex mirror is the point from which the rays appear to come
Since the rays do not actually meet, images formed by convex mirrors are always virtual