Waves Georgia GPS Standards: SPS9. Students will investigate the properties of waves. SPS9a. Recognize that all waves transfer energy. S8P4a: Identify the characteristics of electromagnetic and mechanical waves. S8P4f: Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch.

Key ideas Waves transfer energy There are different types of waves Waves have measurable properties Waves behave in predictable ways

Waves transfer energy Whether we recognize it or not, we encounter waves on a daily basis. Sound waves, visible light waves, radio waves, microwaves, water waves, sine waves, cosine waves, stadium waves, earthquake waves, waves on a string, and slinky waves and are just a few of the examples of our daily encounters with waves. Remember, waves transfer energy.

What is a wave? A wave is a disturbance that transfers energy from one place to another. A wave can be described as a disturbance that travels through a medium (substance or material which carries the wave ) from one location to another location. MECHANICAL waves travel through matter.

Types of Waves: Transverse Waves A transverse wave is a wave in which particles of the medium move in a direction perpendicular to the direction which the wave moves. Transverse waves are always characterized by particle motion being perpendicular to wave motion.

Types of Waves: Longitudinal Waves A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction which the wave moves. Longitudinal waves are always characterized by particle motion being parallel to wave motion. A sound wave is an example of a longitudinal wave. Sometimes these are called compression waves because they bunched-up area is known as a compression. The places where the wave is spaced out are called “rarefactions.”

Types of Waves: Surface Waves A surface wave is a wave in which particles of the medium undergo a circular motion. Surface waves are neither longitudinal nor transverse.

Measurable Properties: Wavelength Anatomy of a wave: Crest: highest point or peak of a wave Trough: the lowest point, or valley of a wave The wavelength of a wave is the distance between identical points in the adjacent cycles of a waveform The distance from crest to crest or trough to trough in a transverse wave OR The distance from compression to compression in a longitudinal wave

Measurable Properties: Amplitude, Frequency & Wave Period The amplitude of a wave is the distance between the peak of a wave and the midpoint of the wave. The amount of energy carried by a wave is related to the amplitude of the wave. The frequency of a wave is the number of cycles that pass the observer in a given time. Hertz is the unit of frequency, and just means how many cycles per second. The wave period is a measure of time – how long it takes for the full wave takes to pass a given point.

Waves behave in predictable ways Waves can interact with matter: Reflection is when waves, whether physical or electromagnetic, bounce from a surface back toward the source. A mirror reflects the image of the observer. Refraction is when waves, whether physical or electromagnetic, are deflected when the waves go through a substance. The wave generally changes the angle of its general direction. Diffraction is when a wave goes through a small hole and has a flared out geometric shadow of the slit. Diffraction is a characteristic of waves of all types.

Wave Interactions Waves can interact with each other: Constructive wave interference increases amplitude –when the crests of two waves overlap Destructive interference decreases amplitude –when the crest of one wave overlaps with the trough of another wave Standing waves are produced whenever two waves of identical frequency interfere with one another while traveling opposite directions. Waves are characterized by fixed points (nodes) which appear to have no displacement. The frequency at which standing waves are produced is called resonance. Resonance occurs when an object vibrating at or near the resonant frequency of a second object causes another object to vibrate. Explore: http://www.sciencejoywagon.com/physicszone/09waves/ Wave Weirdness: Double Slit Experiment: http://www.youtube.com/watch?v=DfPeprQ7oGc

Assignments Note Taking Activity Waves worksheet 1 Waves worksheet 2