Download 9.3 Refraction and Lenses

9.3
REFRACTION AND LENSES

Essential Questions:
1.
2.
3.
What Happens When Light Hits an Object?
What Determines the Type of Image Formed by a Lens?
What Factors Affect the Speed of a Wave?
WHAT HAPPENS WHEN LIGHT HITS AN
OBJECT?

When light hits an object, it can be reflected,
refracted, and/or absorbed.
REFRACTION IN DIFFERENT MEDIUMS
Some mediums cause light to
bend more than others.
 The index of refraction of a
medium is a measure of how
much a light ray bends when it
enters that medium.


The higher the index, the more
the light bends.
PRISMS AND RAINBOWS

Prisms refract different wavelengths of light at
different degrees.


The longer the wavelength, the less it’s bent.
Water droplets produce the same effect.

Rainbows!!!
RAINBOWS!!!
MIRAGES

A mirage is an image of a distant object caused
by the refraction of light.
WHAT DETERMINES THE TYPE OF IMAGE
FORMED BY A LENS?
A lens is a curved piece of glass or other
transparent material that refracts light.
 The type of image formed by a lens depends on
the shape of the lens and the position of the
object.

CONCAVE LENSES
Notice that the light rays are parallel to the
optical axis, an imaginary line that divide a
lens in half.
 The focal point is that point at which refracted
parallel light rays meet.

CONCAVE LENSES

A concave lens is thinner at the center than at
the edges.

Light is bent away from the optical axis and never
meets.

This produces a virtual image because the rays never meet.
CONCAVE LENSES
Concave Lens
A concave lens produces a
virtual image that is upright and
smaller than the object. In the
second diagram, where would
the image be when the two
light rays are extended back to
the same side of
the lens as the object?
CONVEX LENSES

A convex lens is thick at the center than at the
edges.

Light rays that pass through a convex lens are bent
toward the center of the lens.
CONVEX LENSES
Real
How a Convex Lens
Works
The type of image
formed by a convex lens
depends on the object’s
position. Which image is
virtual and which is real?
Virtual
WHAT FACTORS AFFECT THE SPEED OF A
WAVE?

The speed of a wave through a substance is
determined by the substance’s physical
properties.
WHAT FACTORS AFFECT THE SPEED OF A
WAVE?

The speed of light through a medium depends on
how the medium interacts with electric and
magnetic fields.
WHAT FACTORS AFFECT THE SPEED OF A
WAVE?

Temperature, density, and compressibility.

As these increases, the speed of sounds increases.