Section 1: The Nature of Waves. Section 2: Properties of Waves

Transcription

1 Module O: Chapter 1 The Energy of Waves Section 1: The Nature of Waves Section 2: Properties of Waves Section 3: Wave Interactions

2 Section 1 The Nature of Waves Objectives Describe how waves transfer energy without transferring matter. Distinguish between waves that require a medium and waves that do not. Explain the difference between transverse and longitudinal waves.

3 Section 1 The Nature of Waves Wave Energy Waves and Work As a wave travels, it does work on everything in its path. Wave motion is shown on the next slide. Energy Transfer Through a Medium Most waves transfer energy by the vibration of particles in a medium. A medium is a substance through which a wave can travel. Energy Transfer Without a Medium Some waves can transfer energy without going through a medium. Visible light is one example. Waves that do not need a medium are electromagnetic waves.

4 Section 1 Wave Motion

5 Section 1 The Nature of Waves Types of Waves Transverse Waves Waves in which the particles vibrate in an up-and-down motion are called transverse waves. Ex. Electromagnetic waves Longitudinal Waves In a longitudinal wave, the particles of the medium vibrate back and forth along the path that the wave moves. Need a medium The more dense the medium the easier energy transferred Mechanical waves Ex: sound waves

6 Section 1 The Nature of Waves Types of Waves continued Sound Waves Sound waves travel by compressions and rarefactions of air particles. Combinations of Waves A transverse wave and a longitudinal wave can combine to form a surface wave.

7 Section 1 Comparing Longitudinal and Transverse Waves

8 Section 2 Properties of Waves Objectives Identify and describe four wave properties. Explain how frequency and wavelength are related to the speed of a wave.

9 Section 2 Properties of Waves Amplitude What Is Amplitude? The amplitude of a wave is related to its height. A wave s amplitude is the maximum distance that the particles of a medium vibrate from their rest position. Larger Amplitude More Energy A wave with a large amplitude carries more energy than a wave with a small amplitude does.

10 Section 2 Properties of Waves Wavelength What Is a Wavelength? A wavelength is the distance between any two crests or compressions next to each other in a wave. Shorter Wavelength More Energy A wave with a shorter wavelength carries more energy than a wave with a longer wavelength does. The next slide shows how to measure wavelength.

11 Section 2 Measuring Wavelength

12 Section 2 Properties of Waves Frequency What Is Frequency? The number of waves produced in a given amount of time is the frequency. Higher Frequency More Energy If the amplitudes are equal, high-frequency waves carry more energy than lowfrequency waves.

13 Section 2 Properties of Waves Wave Speed What Is Wave Speed? Wave speed is the speed at which a wave travels. Frequency and Wavelength Relationship Three of the basic properties of a wave are related to one another in the wave equation wave speed, frequency, and wavelength. If you know any two of these properties of a wave, you can use the wave equation to find the third. One of the things the wave equation tells you is the relationship between frequency and wavelength. If a wave is traveling a certain speed and you double its frequency, its wavelength will be cut in half.

14 Section 3 Wave Interactions Reflection What Is Reflection? Reflection happens when a wave bounces back after hitting a barrier. Transmitting a Wave Waves are not always reflected when they hit a barrier. If all light waves were reflected when they hit your eyeglasses, you would not be able to see anything! A wave is transmitted through a substance when it passes through the substance.

15 Section 3 Wave Interactions Refraction What Is Refraction? Refraction is the bending of a wave as the wave passes from one medium to another at an angle. Refraction of Different Colors When light waves from the sun pass through a droplet of water in a cloud or through a prism, the light is refracted. But the different colors in sunlight are refracted by different amounts, so the light is dispersed,or spread out, into its separate colors.