Light Electromagnetic waveElectromagnetic wave Needs NO medium to travelNeeds NO medium to travel Transverse wave.Transverse wave. Speed of Light – 3.00.

LightLight

• Electromagnetic waveElectromagnetic wave

• Needs NO medium to travelNeeds NO medium to travel

• Transverse wave. Transverse wave.

• Speed of Light – 3.00 x 10Speed of Light – 3.00 x 108 8 m/s m/s

(In air and in a Vacuum)(In air and in a Vacuum)

Speed of Light

• ALL electromagnetic waves travel at the speed of light

• (Radio, TV, Gamma, Ultraviolet and Infrared. . . See Reference Table)

Dual Nature of Light

• Light sometimes behaves like a particle

• Light sometimes behaves like a wave

White Light

• The light that comes from the sun and other artificial means is called white light or visible light.

• White Light is composed of the colors of the rainbow.

Visible LightVisible Light

• ROY G. BIVROY G. BIV

Light EnergyLight Energy

• Luminous ObjectsLuminous Objects – Objects that – Objects that generate their own lightgenerate their own light

• Illuminated ObjectsIlluminated Objects – Objects that are – Objects that are capable of reflected lightcapable of reflected light

Light ReflectionLight Reflection

Regular ReflectionRegular Reflection Diffuse ReflectionDiffuse Reflection

Refraction of LightRefraction of Light

Refraction of LightRefraction of Light

• Speed of light is dependent on the Speed of light is dependent on the medium it is traveling throughmedium it is traveling through

• Optical densityOptical density ( (How well light can pass through)

Index of Refraction

• Index of Refraction – Number that tells how optically dense an object is based on the speed of light through it.

Index of Refraction ValueIndex of Refraction Value

• Ratio of the speed of light in a vacuum Ratio of the speed of light in a vacuum to the speed of light in the material.to the speed of light in the material.

n – index of refractionn – index of refraction

c – speed of light (m/s)c – speed of light (m/s)

v – velocity (m/s)v – velocity (m/s)

v

cn

Snell’s Law

• As light speeds up, it bends AWAY from the normal

• As light slows down, it bends TOWARDS the normal

• Using Snell’s Law and the values for n in the Using Snell’s Law and the values for n in the diagram below, draw arrows to show the path diagram below, draw arrows to show the path through the layers of different materials.through the layers of different materials.

Air (1.0)Flint Glass (1.61)

Water (1.33)

Diamond (2.42)

DiffractionDiffraction

• Bending of a wave around an obstacleBending of a wave around an obstacle

• Single Slit DiffractionSingle Slit Diffraction

DiffractionDiffraction

• Double Slit DiffractionDouble Slit Diffraction

Diffraction

• Size of opening and wavelength affect the diffraction pattern

• Greatest diffraction pattern occurs with a long wavelength and narrow opening

PolarizationPolarization

• Unpolarized light – Light waves which are Unpolarized light – Light waves which are vibrating in more than one plane (Sun, vibrating in more than one plane (Sun, lamps, candle)lamps, candle)

• Polarized Light – Light waves in which the Polarized Light – Light waves in which the vibrations occur in a single planevibrations occur in a single plane

PolarizationPolarization

• Polarization – process of transforming Polarization – process of transforming unpolarized light into polarized light. unpolarized light into polarized light.

• Uses - SunglassesUses - Sunglasses

WARM-UP

• The speed of light in Lucite is _________?

• The speed of light in goop is 2.56x108 m/s. What is the index of refraction of goop?

Lab #17 and #18Lab #17 and #18

• Lab #17 Lab #17 – Problem: How are the angle of incidence and Problem: How are the angle of incidence and

the angle of the angle of reflection reflection related?related?

• Lab #18Lab #18– Problem: How are the angle of incidence and Problem: How are the angle of incidence and

the angle of the angle of refractionrefraction related? related?