Preview Key Ideas Bellringer What Is a Wave? Vibrations and Waves Transverse and Longitudinal Waves Surface Waves SECTION 1: TYPES OF WAVES

〉 What does a wave carry? 〉 How are waves generated? 〉 What is the difference between a transverse wave and a longitudinal wave? 〉 How do the particles in ocean waves move? KEY IDEAS

1.Imagine throwing a rock into a pond or lake. Describe the effect that the rock has on the surface of the water. 2.When surfing, a person moves just ahead of a wave. Where does the energy come from to move the surfer through the water? 3.What happens to a string on a guitar or other stringed instrument when it is plucked? BELLRINGER

〉 What does a wave carry? 〉 A wave is a disturbance that carries energy through matter or space. WHAT IS A WAVE?

Most waves travel through a medium. medium: a physical environment in which phenomena occur Ex. Air, Water, Earth mechanical wave: a wave that requires a medium through which to travel examples: sound waves, water waves, earthquakes WHAT IS A WAVE?, CONTINUED

VISUAL CONCEPT: ELECTROMAGNETIC WAVES Electromagnetic waves do not require a medium. electromagnetic wave: a wave that consists of oscillating electric and magnetic fields, which radiate outward at the speed of light examples: visible light waves, radio waves

VISUAL CONCEPT: TSUNAMI Waves transfer energy. Tsunamis carry enough energy to cause damage to coastal towns. The energy of normal ocean waves breaks up rocks into pieces to form sandy beaches.

Energy may spread out as a wave travels. When sound waves travel in air, the waves spread out in spheres. As the waves travel outward, the spherical wave fronts get bigger, so the energy spreads out over a larger volume. WHAT IS A WAVE?, CONTINUED

〉 How are waves generated? 〉 Most waves are caused by vibrating objects. The sound waves produced by a singer are caused by vibrating vocal cords. Electromagnetic waves may be caused by vibrating charged particles. For mechanical waves, the particles in the medium through which the wave passes vibrate, too. VIBRATIONS AND WAVES

The mechanical energy of a vibrating mass-spring system changes form. This type of vibration is called simple harmonic motion. VIBRATIONS AND WAVES, CONTINUED

A wave can pass through a series of vibrating objects. The disturbance travels down the row as energy is transferred from one mass to another. Wave particles move like masses on springs. damped harmonic motion. VIBRATIONS AND WAVES, CONTINUED

VISUAL CONCEPT: TRANSVERSE WAVE Transverse waves have perpendicular motion. transverse wave: a wave in which the particles of the medium move perpendicularly to the direction the wave is traveling

VISUAL CONCEPT: LONGITUDINAL WAVE Longitudinal waves have parallel motion. longitudinal wave: a wave in which the particles of the medium vibrate parallel to the direction of wave motion

Waves have crests and troughs or compressions and rarefactions. TRANSVERSE AND LONGITUDINAL WAVES, CONTINUED –crest: the highest point of a transverse wave –trough: the lowest point of a transverse wave –compressions: the crowded areas of a longitudinal wave –rarefactions: the stretched-out areas of a longitudinal wave

〉 How do the particles in ocean waves move? 〉 The particles in a surface wave move both perpendicularly and parallel to the direction in which the wave travels. surface waves: waves that occur at the boundary between two different mediums, such as water and air SURFACE WAVES

VISUAL CONCEPT: FORMATION AND MOVEMENT OF OCEAN WAVES