WAVES CARRY ENERGY! MECHANICAL WAVES Waves are rhythmic disturbances that carry ENERGY without carrying matter. Molecules transport the energy in a wave by colliding with the molecules around them. Mechanical waves travel through matter by creating vibrations in a medium – solid, liquid or gas. Examples: Sound, water or seismic waves. MECHANICAL WAVES Use matter to transfer ENERGY from particle to particle Matter = Medium (requires it) TRANSVERSE COMPRESSIONAL (Longitudinal)

WAVE PROPERTIES WAVELENGTH CREST AMPLITUDE TROUGH FREQUENCY POSITION TROUGH FREQUENCY CREST – highest point of a wave TROUGH – lowest point of a wave WAVELENGTH – distance from peak to peak AMPLITUDE – the distance a wave rises/falls from its rest position FREQUENCY – the number of waves passing a given point

Frequency and Wavelength Longer wavelengths Larger frequencies result in smaller result in shorter frequencies. wavelengths. As the frequency of a wave increases, its wavelength decreases. Frequency and wavelength are related!

TRANSVERSE WAVES EXAMPLES: oscillating, repetitive motion in which the medium moves at right angles to the wave direction particles of the medium moving perpendicular (moves at right angle) WAVELENGTH CREST AMPLITUDE TROUGH EXAMPLES: Slinky, secondary seismic wave, ocean waves, light waves, guitar strings, and a stadium wave

] ] ] COMPRESSIONAL WAVES particles of the medium moving parallel to the direction of the wave oscillating, repetitive motion that moves in the same direction as the medium matter in the medium moves forward or backward in the same direction of the wave Transfers energy from molecule to molecule through solids, liquids & gases Needs a medium to travel – space is a vacuum without air – sound does not travel in space ] RAREFACTION ] ] COMPRESSION WAVELENGTH EXAMPLES - Sound, dominoes, primary seismic waves, bats hearing, sonar

Electromagnetic waves are not caused by a disturbance of particles in a medium. Instead, it is produced by an interaction between an electric and a magnetic field. Field - force or push in a region Speed of light – 300,000 kmps Medium - matter Electromagnetic waves travel in a vacuum at the same speed

ELECTROMAGNETIC SPECTRUM Visible Light 0.000,000,000,000,000,1 0.000,000,000,000,01 0.000,000,000,001 0.000,000,000,1 0.000,000,01 0.000,001 0.000,1 0.01 1 100 10,000 1,000,000 100,000,000 Gamma Rays Radio waves X-rays Microwave Cosmic rays Ultraviolet Infrared HIGH LOW Frequency Short Long Wavelength (192)

ELECTROMAGNETIC WAVES Are transverse waves that do not require matter to carry energy. They are produced by the motion of electrically charged particles. They can travel through solid, liquids or gas faster than mechanical waves. They can also travel through space, or through a vacuum where no matter exist.

LIGHT Light is a electromagnetic wave that travels through air at about 300,000 km/s. Bright lights have greater amplitudes (more energy) than the waves that make up dim light. Because frequency and wavelength are related, either the wavelength or frequency of a light wave determines the color of the light. Blue light has a larger frequency and shorter wavelength than red light. Red light has a shorter frequency and a longer wavelength. Light travels faster through gases than in solids or liquids. Example: speed of light is one and a half times faster in air than it is in glass.

LIGHT WAVE BEHAVIOR Reflected Absorbed Transmitted Light rays that come in contact with a object that reflects it will bounce right back at the same angle it came in at - like your reflection In a mirror. Reflected Absorbed Transmitted Light rays that come in contact with a dark object will be absorbed into it, making the object warmer - like your dark colored shirt or car. Light rays that come in contact with something that is translucent, or clear, will “transmit” or go through the object - like a window or a glass.

A MIRAGE IS AN ILLUSION CAUSED BY THE REFRACTION OF LIGHT WAVES, MAKING OBJECTS THAT ARE FAR AWAY TO BE NEARBY, FLOATING IN THE AIR OR UPSIDE DOWN.

Light rays refract as they enter and leave each rain drop Light rays refract as they enter and leave each rain drop. Each color refracts at different angles because of their different wavelengths, so they separate into the colors of the spectrum.

As sunlight passes through the atmosphere, its wavelength is scattered by particles of dust in the air. Red and yellow wavelengths pass through the air directly, while blue light is scattered. It is this scattered blue light (short wavelength) that reaches our eyes when we see blue sky.

REFRACTION Examples: Eyeglasses Binoculars Telescopes Microscopes Refraction is the bending of a wave as it moves from one medium into another. Air (less dense) Water (dense) Normal Examples: Eyeglasses Binoculars Telescopes Microscopes ANGLE OF INCIDENCE Refracts - - - - - - - - - - - - - - - - Angle of refraction

Incident Ray Normal Reflective Ray Reflection occurs when a wave strikes an object and bounces off.

INTERFERENCE Destructive – a wave with a smaller amplitude is formed. The ability of 2 waves to combine and form a new wave when they overlap. Constructive = combines to make a new wave, increasing its amplitude. INTERFERENCE Pg. 202

R O Y G B I V

The diffraction grating has thousands of tiny parallel lines etched into it. Diffraction is the bending of waves around barriers or through openings. What colors do you see through the diffraction grating? What are some examples of patterns you can observe? Where did all the beautiful colors come from? Have you ever used a prism to separate white light into its many colors? If so, what did you observe?

SOUND Sound is a mechanical wave that travels through air at about 340 m/s or 1100 ft. per second. Loud sound waves are greater amplitudes than soft sound waves. Loud sounds carry more energy than soft sounds. Sound travels faster in a solid than a liquid, and faster in a liquid than a gas. In a sound wave, either the wavelength or frequency determines the pitch. Pitch is the high or low of a sound. Sound level (loudness) is measured in units called decibels. Vocal cords produce sound by vibration. As the frequency of a sound wave increases, its wavelength decreases.

DIFFRACTION Diffraction is the bending of waves around a barrier. Example: Music going into another room. Light shining into the next room. Light waves do not diffract as much as sound waves do. DIFFRACTION 1.What colors do you see through the diffraction grating? 2. What are some examples of patterns you can observe? 3. Where did all the beautiful colors come from? 4. Have you ever used a prism to separate white light into its many colors?

Sound – Pitch and Loudness Pitch - depends on frequency High frequency – high pitch Low frequency – low pitch Loudness – depends on energy of amplitude Intensity of the wave – amount of energy in a certain amount of time The greater the amplitude, the louder the sound

] ] ] COMPRESSIONAL WAVES particles of the medium moving parallel to the direction of the wave oscillating, repetitive motion that moves in the same direction as the medium matter in the medium moves forward or backward in the same direction of the wave Transfers energy from molecule to molecule through solids, liquids & gases Needs a medium to travel – space is a vacuum without air – sound does not travel in space ] RAREFACTION ] ] COMPRESSION WAVELENGTH EXAMPLES - Sound, dominoes, primary seismic waves, bats hearing, sonar