A laser pointer is aimed at the surface of a flat mirror. Draw the laser beam after it hits the surface of the mirror.

Ray – represents the direction of the wavefront.

Normal – the line drawn perpendicular to a barrier.

Incident Ray – the ray approaching a boundary.

Reflected Ray – the ray that is rebounding (leaving) from a boundary.

Label the following components of the ray diagram below; incident ray, reflected ray, normal, angle of incidence, angle of reflection.

Law of Reflection – the angle of incidence equals the angle of reflection.

θi = θr

Using a protractor, draw and label the normal line and the reflected ray for each diagram below. Measure and label the angle of incidence and the angle of reflection.

Approximately how far up the mirror from the floor does this ray strike the mirror?

Image – formed by the reflection of light waves off of a mirrored surface.

Image point – the location behind the mirror where all the light from an object appears to diverge from. When reflected rays are extended backwards, each line will intersect at this point.

1. Virtual image – an image is formed in a location where light does not reach, though it appears to the observer as though the light were coming from that position.

2. Left-right reversal – object’s left appears as image’s right, and visa versa.

3. Upright – image is not reversed vertically

4. do = di (distance from object to mirror = distance from image to mirror)

5. Magnification of 1 - image and object have equal dimensions

Refraction – a change in direction, or bending of a wave, at the boundary between two mediums.

Caused by a change in speed

Wave must hit boundary at an angle.

Absolute Index of Refraction (n) - the ratio of speed of light in a vacuum (c), to the speed of light in a material medium (v).

cn

v

Monochromatic: light that is described by only one frequency. (laser light)

Polychromatic: light that is described by many different frequencies. (white light)

Wave travels into…

Change in Wave Speed

Direction of Bending

with Respect to the Normal

Change in Wavelength

More Dense Medium

Less Dense Medium

Equally Dense

Medium

2 1 1

1 2 2

n v λ= =

n v λ

Snell’s Law – allows us to find the angle of incidence or refraction of light waves traveling from one medium to another.

n1 sinθ1 = n2 sinθ2

air

water

air

water

air

water

48.75346°

Critical Angle (θc)– the incident angle unique to a substance that causes the refracted ray to lie along the boundary of the substance.

* Not in Reference Table

-1c

1.00θ = sin

n

Total Internal Reflection – occurs when light is incident on the boundary to a less optically dense medium at an angle so large there is no refracted ray.

Limits how much you can see out of the water.

*Fiber Optics can transmit audio, video, etc through coded light signals.

* Light enters at critical angle and

reflects along cable. Cladding

(outer layer) prevents light

from scattering.

Slow to Fast = Bends AwaySlow to Fast = Bends Away

Air just above Air just above pavement heats pavement heats

up (becomes less up (becomes less dense). dense).

Slow to Fast = Bends AwaySlow to Fast = Bends Away

Fast to Slow = Bends TowardsFast to Slow = Bends Towards

After the sun has After the sun has actually set, it is actually set, it is

still visible still visible because of because of

refraction of light refraction of light over the horizon over the horizon

through the through the thicker thicker

atmosphere.atmosphere.FSTFST

Rays from top of sun Rays from top of sun are alsoare also

 refracted, but not as  refracted, but not as much becausemuch because they enter the  they enter the

atmosphere at a less atmosphere at a less oblique angle.  Thus, oblique angle.  Thus,

the top of the the top of the  sun is also flattened,  sun is also flattened, but not as much as but not as much as

the bottom.the bottom.

If you ever have to spear fish, aim BELOW the fish.If you ever have to spear fish, aim BELOW the fish.

The Archer fish’s view of The Archer fish’s view of an insect is distorted due an insect is distorted due

to refraction of light. It to refraction of light. It over comes this over comes this disadvantage by disadvantage by

shooting “off target.”shooting “off target.”

Dispersion – the separation of white light into different colors rays. Different frequencies (colors) travel at

different speeds through the medium.

Blue Bends BestBlue Bends Best