Refraction and Lenses

Refraction and
Lenses

A. Refraction of Light

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1. Light changes direction as it passes
from one kind of material, or medium,
into another

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2. Refraction is the bending of a wave
as it changes speed while it moves from
one medium to another

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a. All transparent media have an index
of refraction.

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b. A medium in which light moves slowly
has a(n) high index of refraction. A
medium in which light move quickly has
a(n) low index of refraction.

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3. As a ray of light travels at an angle
from a faster medium into a(n) slower
medium, the light ray bends toward the
normal.

Multiple Choice

In which material would light travel the fastest?

• Solid

• Liquid

• Gas

• Vacuum

Reorder

Place the colors in order of how they would refract. Slowest to Fastest

Here is a hint the higher the energy the faster more it will refract

• Red

• Orange

• Yellow

• Green

• Blue

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

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B. Lenses

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1. A transparent object that has at least
one curved side that causes light to
change direction is called a(n) lens.

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a. A(n) convex lens is a lens that is
thicker in the middle than at the edges.
Light rays that move through a convex
lens move together, or converge.

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b. A(n) concave lens is a lens that is
thicker at the edges than in the middle.
Light rays that move through a concave
lens spread apart, or diverge.

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2. A magnifying glass is a(n) convex
lens; the light rays bend toward the
normal and toward the optical axis.

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a. A convex lens has a(n) focal point
along the optical axis where the rays of
light passing through it converge.

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b. When you use a convex lens to look
at an object that is farther away than
the focal length of the lens, the image
is inverted, real, and smaller than the
object.

Multiple Choice

The place where al of the light rays converge is called the _______________

• Focus knob

• Focal point

• Divergent point

• Convex point

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3. With a concave lens, the normal
bends away from the curved surface, so
the light rays bend away from the
normal, which is also away from the
optical axis.

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4. A concave lens forms a(n) virtual
image that is smaller than the object.

Labelling

Label each type of lens

Drag labels to their correct position on the image

Concave Lens

Convex Lens

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C. Refraction and Wavelength

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1. Colors of light that have a(n) shorter wavelength
and a higher frequency slow down more when they
pass at an angle into a slow medium; for this
reason, the color red refracts (bends) the least and
the color violet refracts (bends) the most.

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2. A prism is a(n) triangular piece of
glass that refracts white light when it
enters and leaves the prism, causing
the colors of light to spread out.

Multiple Choice

The colors of white light break into component colors because they refract as they go through a prism. The refract differently because they are traveling at different________________

• Speeds

• Frequencies

• Mediums

• Angles

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3. A(n) rainbow forms when sunlight
passes through raindrops, which refract
light in the same way that a prism does;
this causes the colors of light to spread
out.

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D. Detecting Light

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1. The parts of the human eye focus
light and send signals to the brain.

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2. Cells on the retina allow you to see
color and shades of gray.

Labelling

Label The primary colors of light

Drag labels to their correct position on the image

Green

Red

White

Blue

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3. A person who has normal vision has a
lens that focuses light directly onto the
retina.

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a. For a person who is nearsighted, the
image forms in front of the retina; such
a person can correct his or her vision
using a(n) concave lens.

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b. For a person who is farsighted, the
image forms behind the retina; such a
person can correct his or her vision
using a(n) convex lens.

Match

Match the following eyeglass lens with the type of vision it corrects

• Nearsighted (Can see things close up)

• Farsighted (Can see things far away)

• Color Blindness (Difficulty distinguishing colors)

Concave Lens

Convex Lens

You don't need glasses for this

• Concave Lens

• Convex Lens

• You don't need glasses for this

Multiple Choice

What happens to light as it passes from one medium to another?

• It speeds up

• It changes direction

• It stops

• It reflects back at the source

Multiple Choice

A student placed a pencil in a cup of water. The pencil appears broken because light

• 
  always travels in a straight line.

• 
  bends when it passes through water.

• 
  makes the water in the glass evaporate.

• reflects the pencil on the water's surface.