Reflection and Refraction of Light Concepts

Explain the frequencies and energy on the electromagnetic spectrum

At the start

Lower frequency

Lower energy

At the end:

Higher frequency

Higher energy

Microwaves

Overlap with radio waves

Ex. Microwaves, cell phones, wifi

Use Anti Nodes (max), And Nodes (low)

Infrared

Felt as heat by skin

Night vision, remote controls

Visible light

ROGBIV is the order of frequencies

How does frequencies effect visible light

Diff. frequencies=diff colors

How does amp effect color

Diff. Amps = Diff intensities of color

Ultraviolet

Higher energy waves that can be dangerous to humans (damage DNA)- makes vitamin d in our skin

Used to:

Black lights

sterilizing medical equipment

Tanning beds

X-Ray

Can damage human cells

Used for medical imagining, airports, cancer treatment

Gamma ray

Highest energy, most dangerous

Smallest wavelength

Used for nuclear radiation and cancer treatments.

Explain how light travels

Light travels in a straight line but in order to see something light must "bounce" off an object into our eyes

What is a reflected ray

The ray of light that bounces off a surface

Incident ray

an incoming ray of light (before it is reflected or refracted)

Specular Reflection

a reflection produced by a smooth surface in which parallel light rays are reflected in parallel

Diffuse Reflection

Reflection that occurs when parallel rays of light hit a rough surface and all reflect at different angles

Reflected Images and Plane mirror

The virtual image is:

The same size as the object

Upright

Left-right reversed

As far behind the mirror as the object is in front of the mirror

Lights speed

Vacuum, gas, liquid, solid

Snell's Law

n1sinθ1 = n2sinθ2. When n2>n1, light bends toward the normal. When n2

Convex Mirror

A mirror that curves outward and reflects light outward.

Concave Mirror

A mirror that curves inward and can focus light to a point.

Index of Refraction (n)

The ratio of the speed of light in vacuum to the speed of light in the medium.

Speed of light in vacuum

3 x 10^8 m/s

Speed of light in diamond

1.25 x 10^8 m/s

Why do diamonds sparkle?

Light changes speed when it enters a new medium.

Bending of Light

Light bends towards the normal when it goes from less dense to more dense and away from the normal when it goes from more dense to less dense.

Refraction

The change in direction of a wave passing from one medium to another caused by its change in speed.

Angle of Incidence (𝜃1)

The angle between the incident ray and the normal line at the boundary of two media.

Angle of Refraction (𝜃2)

The angle between the refracted ray and the normal line at the boundary of two media.

Critical Angle (θc)

The angle of incidence above which total internal reflection occurs, defined by θc = sin-1(n2/n1).Fno

Total Internal Reflection (TIR)

The complete reflection of a light ray back into a medium when it hits the boundary at an angle greater than the critical angle.

Law of Reflection

The angle of incidence is equal to the angle of reflection.

Normal Line

An imaginary line perpendicular to the boundary at the point of incidence.

What is differaction

Waves bend around obstacles in their path

What is poissons spot

A bright spot that appears at the center of a circular object's shadow, proving light behaves like a wave due to diffraction and constructive interference

Polorazation

Polarization is when light waves are filtered so they vibrate in only one direction. This only happens with transverse waves, like light, and is evidence that light behaves as a wave, not a particle

Photoelectric Effect

The emission of electrons from a material when light of certain frequencies shines on the surface of the material

Photons either supply enough energy to eject an electron or they don't- light can behave as particles

Explain threshold frequency and amp.

Any light above the threshold frequency gives electrons enough energy to eject

Amplitude doesn't affect electrons unless above threshold frequency. Then, amplitude only increases the number of ejected electrons, not their energy.

Wave Particle Duality

Light behaves like a wave when it spreads, bends, and interferes, and like a particle when it transfers energy in small, exact packets called photons.