Physics 410

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# Physics 410 - PowerPoint PPT Presentation

Physics 410. Light and Color Chapter 14. Doppler Effect. the change in wavelength due to motion of the source or observer &quot;Wheeeeeeeeeeee…….Oooooooooooooo” Examples: Water, Sound, and Light. Wavelength. Source at Rest. What happens when the source in in motion?. Movie #1. Java.

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### Physics 410

Light and Color

Chapter 14

Doppler Effect
• the change in wavelength due to motion of the source or observer
• "Wheeeeeeeeeeee…….Oooooooooooooo”
• Examples:
• Water, Sound, and Light

Wavelength

Source at Rest

Long Wavelength

Low Frequency

Low Pitch

Ooooooo!!!

Short Wavelength

High Frequency

High Pitch

Weeeeeeeee!!!

As a team, describe what happens to the wavelength, frequency, and pitch both in front of and behind a moving sound source.

Source in Motion

Doppler Effect
• Examples:
• moving cars and trains
• Sound
• Movie #2
• moving buzzer in a nerf ball (in class)

R

O

Y

G

B

I

V

The Electromagnetic Spectrum
• .

Microwaves - used to cook

Infrared - felt as warmth

Visible Light - detected by your eyes

Ultraviolet - causes sunburns

X-rays - penetrates tissue

Gamma Rays - most energetic

Mnemonic?

Raging Martians Invade Roy G. Biv

Using X-rays and Gamma Rays

The Electromagnetic Spectrum

Microwaves

Infrared

Visible Light

Ultraviolet

X-rays

Gamma Rays

Which form of light has the …longest wavelength?

…highest frequency? …highest energy?

…fastest speed?

### Physics 410

Light and Color

Chapter 14

How to Study
• Read the chapters in the syllabus and focus on the topics covered in class.
• Chapter 13 - Waves and Sound
• Chapter 14 - Light and Color
• Chapter 18 - Atomic Models
• Chapter 15 - Reflection and Refraction
• Review your notes and class exercises.
• Use the access code on the inside cover you’re your book to gain access to example questions and flashcards online.
• http://www.physicsplace.com/
Things that create a Spectrum
• Prism
• Raindrops
• CD’s
• Diffraction Grating
Incandescence
• Hot, dense solids produce a continuous spectrum.
• Demo - an incandescent light bulb and diffraction gratings

Continuous Spectrum

Creating a Spectroscope
• Roll up and tape black paper to form a tube.
• Cover end of the tube with foil.
• Use a pencil to make a hole in the foil.
• Temporarily tape the diffraction grating over the other end of the tube.
• Observe several light sources.
Emission Spectra
• Hot gas produces a bright line emission spectrum.
• Demo - hot hydrogen gas and diffraction gratings

Emission Spectrum

Hydrogen

Helium

Oxygen

Carbon

Every element can be “fingerprinted” by it spectra.

Structure of the Atom
• Proton
• Neutron
• Electron
• Energy Levels
Excitation
• When an electron is raised to a higher energy level, the atom is said to be excited.
Emission
• When the electron returns to a lower energy level, energy is released in the form of light.
• Glowing object colors:
• Reddish coolest glowing object
• Orange-ish
• Yellowish
• White
• Bluish  hottest glowing object
Object Names
• Incandescent Light Bulb
• Bright Plate #1 __________
• Bright Plate #2 __________
• Bright Plate #3 __________
Object Names
• Filter #1 __________
• Filter #2 __________
• Filter #3 __________
• Filter #4 __________

Spectra

Chapter 18

### Physics 410

Reflection and Refraction

Chapter 15

Law of Reflection
• “The angle of incidence equals the angle of reflection.”
• This is true for both flat mirrors and curved mirrors.
• Concave Mirror
• Convex Mirror
Types of Reflection
• Specular Reflection - images seen on smooth surfaces (e.g. plane mirrors)
• Diffuse Reflection - diffuse light coming from a rough surface (cannot see a reflection of yourself)
• Movie
Supplemental Handouts
• Make a Kaleidoscope
• Funny Face
• Reverse Images
• Curved Mirrors and Smoke
Principle of Least Time
• Fermat\'s principle - light travels in straight lines and will take the path of least time

A

B

Wrong Path

True Path

MIRROR

Reflection Demonstrations
• Convex and Concave Mirrors
• Candle in Water Video (Movie)
• Terminator II Movie

### Physics 410

Reflection and Refraction

Chapter 15

Refraction
• Refraction is the bending of light when it passes from one transparent medium to another.
• This bending is caused by differences in the speed of light in the media.
• WATER WAVE MOVIE
Refraction

Light Beam

Normal Line

Fast

AIR

WATER

Slow

Refraction Examples
• Light slows down when it goes from air into water and bends toward the normal.
• An Analogy: A car slows down when it goes from pavement onto gravel and turns toward the normal. MOVIE
• Index of Refraction

n=c/v

Refraction

Observer

AIR

WATER

False Fish

True Fish

Broken Images
• Broken Pencil Movie
Lenses
• Converging Lens
• A lens that is thicker in the middle and refracts parallel light rays passing through to a focus.
• Diverging Lens
• A lens that is thinner in the middle than at the edges, causing parallel light rays to diverge.
• Team Exercise: Lens sorting
Dispersion...
• …is the separation of white light into pure colors (ROY G. BIV).
• Dispersion Examples:
• Prisms
• Diffraction Gratings
• CD’s
• Raindrops
Rainbows
• Raindrops refract, reflect and disperse sunlight.
• Rainbows will always appear opposite of the Sun in the sky.
• You cannot run from or run to a rainbow!
• How can you make a rainbow?
Total Internal Reflection...
• …is the total reflection of light traveling in a medium when it strikes a surface of a less dense medium
• Demo - Laser and light pipe
• Example: Optical Fiber Ring
• Laser Underwater Movie
• Woman Edge Pool Movie

AIR

Critical Angle

WATER

Total

Internal

Reflection

Light

Source

Diffraction
• a modification which light undergoes in passing by the edges of bodies or through narrow slits
• …and in which the rays appear to be deflected and to produce fringes of parallel light and dark or colored bands
• Water Wave Interference Movie
• Multiple Slit Interference Movie
Atmospheric Refraction
• Our atmosphere can bend light and create distorted images called mirages.
• What causes stars to twinkle?
• Atmospheric Turbulence

Mirage

Cool air

Warm air

Surface of water?

Because of atmospheric refraction,

we have lingering, elliptical sunsets.

Sun

Earth

Sun

http://virtual.finland.fi/stream/The_Green_Flash_on_video.ramhttp://virtual.finland.fi/stream/The_Green_Flash_on_video.ram