Waves

1 / 51

# Waves - PowerPoint PPT Presentation

Waves. http://ngsir.netfirms.com/. Wave. Rhythmic disturbance that carries energy through matter or space. Types of Waves. Mechanical Waves Require a medium Electromagnetic Waves Move because of an electromagnetic force field; don’t need a medium. Types of Mechanical Waves. Transverse

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about ' Waves' - sherry

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Waves

http://ngsir.netfirms.com/

Wave
• Rhythmic disturbance that carries energy through matter or space.
Types of Waves
• Mechanical Waves
• Require a medium
• Electromagnetic Waves
• Move because of an electromagnetic force field; don’t need a medium.
Types of Mechanical Waves
• Transverse
• Vibration is perpendicular to the direction of wave movement
• Longitudinal
• Vibration is parallel to wave motion.
• Surface Waves
• Have characteristics of both
Wave Properties
• Amplitude
• Displacement from position of rest
• Depends on how wave is generated
• More “work” gives a larger amplitude
Wave Properties
• Wavelength
• Distance of one wave from similar points (crest to crest or trough to trough)
• Represented with λ
Wave Properties
• Period
• The time it takes for one wavelength to pass
• Represented with T, measured in seconds
Wave Properties
• Frequency
• Number of oscillations the wave makes each second.
• Measured in hertz (Hz)
Wave Properties
• Speed
• Depends on the material the wave is traveling through
• Speed = λf
Interference
• The result of having two waves in the same place at the same time
• Also known as superposition
• The waves will either combine or cancel each other out
Types of Interference
• Destructive Interference – amplitudes are displaced in opposite directions, so they cancel each other out when meeting.
• Constructive Interference – amplitudes in same direction; add together
Standing Waves
• When waves’ reflections interfere constructively with each other.
• Node – doesn’t move at all
• Antinode – sees the largest displacement

Resonance
• the tendency of a system to oscillate with greater amplitude at some frequencies than at others
Sound
• Sound waves
• Pressure variation transmitted through matter.
• Speed depends on the material traveling through
Loudness
• Depends on the amplitude of the pressure wave.
• Remember more amplitude = more energy

Pitch
• Related to the frequency of the vibration

Doppler Shift
Light
• We refer to light as the part of the electromagnetic spectrum that is visible to our eyes.

Electromagnetic Spectrum
• Visible light is only one small part of the broad spectrum of electromagnetic waves.
Light
• What we see as “white light” is actually a combination of all colors at once.

Name that band and album.

Perceiving Colors
• The color you see on an object is actually being absorbed by the object – what reaches our eye is everything BUT that color.
Polarization
• Light (ER) vibrates in two directions. Polarizing filters reduce the motion in one of the directions.

http://www.olympusmicro.com/primer/lightandcolor/polarization.htmlhttp://www.olympusmicro.com/primer/lightandcolor/polarization.html

http://www.sunglasswarehouse.com/thesunauthority/polarization-test

Polarization

Reflection
• Law of Reflection
• Angle of Incidence equals Angle of Reflection
Reflection
• Regular Reflection
• Smooth Surface
Reflection
• Diffuse Reflection
• Rough Surface
• Light is scattered

Refraction
• The bending of light waves at a boundary between two different media
Angle of Refraction
• The angle that a refracted wave makes with the normal
Critical Angle
• The incident angle that will cause a reflected ray to lie along the boundary of a surface.
Total Internal Reflection
• Angle at which the ray is reflected back into the medium

http://w ww.gcsescience.com/pwav44.htm

Diffraction
• Bending of a wave around an obstacle
Dispersion
• The separation of light into its colors
Objects vs. Images
• Object – the source of diverging light waves
• Image – the light that is viewed
Plane Mirror
• Smooth flat surface
Virtual Image
• The point that the eye interprets the light rays as having come from
• In a plane mirror, the image is the same size and distance from the mirror as the object is.
Concave Mirrors
• Curved inward
• Principle axis – straight line to the surface at the center
Concave Mirrors
• Focal point – where the parallel rays meet after reflecting.
• Remember: Angle of incidence equals angle of reflection!
Concave Mirrors
• Focal length – distance from the focal point to the mirror
• Real Image – light rays actually converge at that point (not virtual). Projected image.
Concave Mirrors
• Magnification – the ratio of the size of the image to the size of the object.
• Inside the focal point – forms enlarged virtual images.
• Outside the focal point – forms smaller virtual images that are upside-down.
Convex Mirrors
• Spherical – reflects light from the outer surface.
• Rays always diverge – no real images produced.
Lenses
• Made of a transparent material with a refractive index greater than air.
• Remember:
• Transparent – light goes

through uninterrupted (clear

glass)

• Translucent – light goes

through, but is scattered so

image is not easily seen

(frosted glass)

• Opaque – no light goes

through

Convex Lens
• Thicker at the center than at the edges
• Also known as converging lens
Concave Lens
• Thinnest in the center
• Also known as a diverging lens