1. Ch. 14 Light, Mirrors, & Lenses
Sec. 3
Refraction & Lenses

2. Reminders… the speed of light in empty space is about 300 million m/s
light travels slower through mediums
(slowest through solids, fastest through gases)
Speed of Light Comparison
refraction is the bending of light caused by a change in speed as it passes through different mediums

3. Refraction & Lenses
lens - transparent object w/ at least one curved side that causes light to bend/refract
more curved = bends light more
2 types: convex & concave

4. 2 Types of Lenses Convex Lens Concave Lens
convex lens - thicker in the middle than at edges
like a concave mirror…
causes light rays to come together/converge
distance the object is from the focal point affects image
concave lens – thicker at edges than in the middle
like a convex mirror…
causes light rays to spread out/diverge
forms an upright, smaller image

5. Concave Lens Images
always an upright, smaller image

6. Convex Lens
IF the incoming light is parallel to the optical axis, all the light rays passing through a convex lens pass through the focal point
(distance from this point to the center of the lens is called
the focal length)

7. Convex Lens Images
IF an object is farther than 2 focal lengths from a convex lens…
the image will be upside down
(inverted) & smaller
IF an object is b/w one & 2 focal lengths from a convex lens…
(inverted) & larger
IF an object is closer than one focal length to a convex lens…
the image will be upright &
larger (like a magnifying glass)