# WAVES Mechanical and Electromagnetic

## Presentation on theme: "WAVES Mechanical and Electromagnetic"— Presentation transcript:

WAVES Mechanical and Electromagnetic
TEXT BOOK SOUND AND LIGHT CHP 1-4 Images from pearsonsuccessnet.com

CH 1 LESSON 1 WHAT ARE WAVES
LEARNING OBJECTIVES: Explain what causes mechanical waves. List and describe three types of mechanical waves.

Explain what causes mechanical waves.
WAVE – Is a disturbance involving the transfer of energy from place to place. Most waves need a material to travel through (MEDIUM). Examples of Mediums – Air, Water, Solids MECHANICAL WAVES require two things: Source of energy which creates vibrations A MEDIUM that vibrates

List and describe three types of mechanical waves.
TRANSVERSE: A wave that vibrates at right angles to the direction in which the wave travels (up and down). LONGITUDINAL: A wave that vibrates the medium in the same direction in which the wave travels (back and forth). SURFACE: Combination of transverse and longitudinal waves. Wave passes through the water it vibrates up/down AND back/forth… this causes water molecules to move in circles.

TRANSVERSE WAVE CREST TRHOUGH

LONGITUDINAL RAREFACTION COMPRESSION

SURFACE WAVE

CHP 1 LESSON 2 PROPERTIES OF WAVES
LEARNING OBJECTIVES: Describe the basic properties of waves. Explain how a wave’s speed is related to it s wavelength and frequency.

Describe the basic properties of waves.
AMPLITUDE: Is the max height of the wave from resting position. High waves have more energy! WAVELENGTH: Distance between repeating parts. Crest – Crest Trough – Trough Compression - Compression FREQUENCY: Number of waves per second (Hertz). Higher frequency waves have more energy! SPEED: How far the wave travels in a given time. Speed is affected by medium and temperature.

Text Book pg 12-13

Explain how a wave’s speed is related to it s wavelength and frequency.
The wave speed, wavelength, and frequency are related mathematically: Speed = Wavelength X Frequency If the medium is the SAME, with same temp and pressure, then the speed with be the same!

CHP 1 LESSON 3 INTERACTIONS OF WAVES
LEARNING OBJECTIVES: Describe how reflection, refraction, and diffraction change a wave’s direction.

Describe how reflection, refraction, and diffraction change a wave’s direction.
If a wave hits a surface and cannot pass through, the wave bounces back. Law of Reflection states that the angle of incidence (incoming) EQUALS the angle of reflection.

Describe how reflection, refraction, and diffraction change a wave’s direction.
Refraction is the bending of waves due to change in speed. Waves bend when 1 side of the wave changes speed before the other side. Waves do NOT bend if: it enters new medium at a RIGHT angle new medium has SAME speed.

Describe how reflection, refraction, and diffraction change a wave’s direction.
When a wave moves around a barrier or through an opening, it bends and spreads out.

CHP 2 LESSON 1 THE NATURE OF SOUND
LEARNING OBJECTIVE: Define sound. Identify factors that affect the speed of sound.

Define sound. Sound is caused by energy creating a disturbance which vibrates a medium (gas, liquid, or solid) and travels through LONGITUDINAL WAVES. Read page 35 in the book – Explain how sound waves form from a drumheads.

Identify factors that affect the speed of sound.
Medium TEMPERATURE: Sound travels SLOWER at lower (colder) temps particles move less Sound travels FASTER at higher (warmer) temps particles move more

Identify factors that affect the speed of sound.
Medium STIFFNESS: Sound travels FASTER in stiffer mediums because it compresses more quickly. faster thru solids, slower thru gases Medium DENSITY: Sound travels SLOWER through denser materials because particles are already very compressed.

CHP 2 LESSON 2 PROPERTIES OF SOUND
LEARNING OBJECTIVES: State what the pitch of a sound depends on. Identify factors that affects the loudness of a sound. Explain what causes the Doppler effect. Tuning Fork Demonstration Video demonstrations-with-tuning-forks

State what the pitch of a sound depends on.
PITCH depends on the wave FREQUENCY of the sound. High frequency waves have a high pitch (soprano singer) Low frequency waves have a low pitch (bass singer)

Identify factors that affects the loudness of a sound.
LOUDNESS of a sound depends on the energy and intensity of the sound wave. More ENERGY creates a greater AMPLITUDE which causes LOUDER SOUND! Loudness is measured in DECIBELS (dB). Sounds over 100 dB can cause damage to ears.

Explain what causes the Doppler effect.
The Doppler Effect occurs because the source causing the waves moves which changes the frequency. The motion causes the waves to either spread OUT or get close TOGETHER: Spread out = lower frequency Close together = higher frequency

CHP 3 LESSON 1 THE NATURE OF ELECTROMAGNETIC W.
LEARNING OBJECTIVES: State what an electromagnetic wave consists of. Draw an electromagnetic wave.

State what an electromagnetic wave consists of.
Electromagnetic waves are TRANSVERSE waves made up of vibrating ELECTRIC and MAGNETIC fields. Electromagnetic waves transfer energy called ELECTROMAGNETIC RADIATION. They DO NOT require a medium, so they can transfer waves through a vacuum or empty space. They move at the SPEED OF LIGHT (300,000km/s)

Draw an electromagnetic wave.

CHP 3 LESSON 2 WAVES OF ELECTROMAGNETIC SPECTRUM
LEARNING OBJECTIVES: Explain how electromagnetic waves are alike and how they are different. Describe the waves that make up the electromagnetic spectrum.

Explain how electromagnetic waves are alike and how they are different.
ALL electromagnetic waves travel at the same speed in a vacuum (light speed). Electromagnetic waves have DIFFERENT wavelengths and frequencies! Long wavelength=low frequency Short wavelengths=high frequency

CHP 4 LESSON 1 LIGHT AND COLOR
LEARNING OBJECTIVES: Describe what determines the color of an opaque, transparent, or translucent object. Explain how mixing pigments is different from mixing light.

What happens to light when it strikes an opaque, transparent, or translucent object.
TRANSPARENT: Light passes through the material without being scattered. (water, air, clear glass) TRANSLUCENT: The material scatters the light as it passes through. (wax paper, frosted glass, fog) OPAQUE: The material reflects or absorbs all of the light (does not pass through).

Describe what determines the color of an opaque object.
The color of an opaque object is the COLOR of the light that is REFLECTED. Pigments absorb specific wavelengths of light, others are then reflected off! RED LIGHT: Apple reflects red Leaves absorb red GREEN LIGHT: Apple absorbs green Leaves reflect green

Explain how mixing pigments is different from mixing light.
PRIMARY COLORS of LIGHT: Red, Blue, Green When the PRIMARY colors of LIGHT are mixed EQUALLY, they produce WHITE LIGHT!

WHITE LIGHT

Explain how mixing pigments is different from mixing light.
PIGMENTS absorb specific wavelengths of light, others are then reflected (color). PRIMARY COLORS of Pigment Yellow, Cyan, Magenta When the PRIMARY colors of PIGMENT are mixed EQUALLY, they produce the color BLACK!

CHP 4 LESSON 2 AND 3 REFLECTION AND REFRACTION
LEARNING OBJECTIVES: Identify kinds of reflection. Explain why light rays bend when they enter a medium at an angle.

Identify kinds of reflection.
REGULAR reflection occurs when light rays hit a smooth surface and reflect at the same angle (mirror image). DIFFUSE reflection occurs when light rays hit uneven surface and reflect at different angles (most objects).

Explain why light rays bend when they enter a medium at an angle.
When light rays enter a new MEDIUM at an angle, 1 side changes speeds before the other side. This causes the ray to bend.

Explain why light rays bend when they enter a medium at an angle.
Light travels fastest in AIR, slower in WATER, and slowest in GLASS. Index of Refraction is a measure of how much a light ray bends. The higher index of refraction, the greater the bend.