Physical Science Chapter 16: SOUND & LIGHT Study Guide This chapter covers..

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1 Physical Science Chapter 16: SOUND & LIGHT Study Guide This chapter covers Sound Sound, including the of sound, musical instruments, the human ear,, and sonar Wave and particle properties of light and the spectrum Reflection of light, including and how we see color Refraction of light, including the use of lenses in, telescopes, and the eye and prisms Properties of Sound Loudness Loudness of sound depends on the Sound waves travel in liquids and than gases In a or solid, the particles are together The are transferred more between particles Some solids (like rubber) vibrations, making waves travel. (Sound proofing) Determined by Depends on your from the The energy of a wave is determined by The greater the amplitude of a waves, the the sound The of a sound describes its Relative intensity-comparing the intensity of a sound with the sound a person can hear, the of hearing 1

2 Is measured in, db Pitch Pitch- defined as the perceived or Determined by A high-pitched note is made by very rapid (air in a flute) A low-pitched note is made by vibrations (cello strings) pitch corresponds to frequency; pitch sounds corresponds to frequency Human hearing Humans hear sound waves in a limited range (infrasonic) consists of waves where f< Hz Ultrasound ( ) consists of waves where f> Hz Many animals can hear of sound outside the range of human hearing Human hearing from 20 Hz Hz Musical Instruments Musical rely on standing waves give every instrument a sound Harmonics are whole-number of a frequency Resonance is an effect in which the of one object causes the vibration of another object at a Instruments use resonance to sound (guitar) Hearing and the Ear The human ear is a very organ that senses in the air, amplifies them, and transmits to the brain Sound waves cause in the ear to (eardrum) Vibrations pass through three in the ear: outer, middle, inner Resonance occurs in the ear 2

3 The brain impulses from the nerve fibers as a sound with a specific frequency Ultrasound and Sonar Like all, sound reflect The reflection of sound waves can be used to determine and to create maps and Sonar is a system that uses reflected sound waves to determine the to and of objects Sonar is used for location can be determined by the formula d=vt Ultrasound imaging is used in Ultrasound does damage human cells At high, ultrasound can travel through most materials. The higher the frequencies of waves in a, the shorter the wavelength Ex. 15 million Hz wavelength = 1 mm 16.2 Waves and Particles Light produces patterns like water waves Light can be as a wave (Produces interference patterns.) The wave model of light cannot explain some Ex. Light striking a piece of metal causes to fly Light can be as a stream of particles A is a particle of light Photons do not have mass; they are like of energy. The energy of a is located in a particular place. Light The model of light used, waves or stream, depends on the Some scientists believe that light has a nature Either of light yields good results The interference of light is best using the wave model 3

4 Light traveling across an space without a is best explained using the model Both models are accepted by The energy of light is to frequency Each of light can be thought of as carrying a small amount of energy. The amount of this energy is to the frequency of the corresponding wave. Let s look at this in terms of the visible light segment of the EM spectrum. The speed of light depends on the In a vacuum, light travels at the same, c =3 x 108 m/s. travels faster than the speed light. Light is the signal in the electromagnetic spectrum. When light passes through a, it travels than it does in a vacuum. Transparent mediums like air, water, glass Characteristics of Light The of light depends on. Intensity is the rate at which or any other form of flows through a given area of space The intensity of light as the light spreads out. Types of Light-the EM Spectrum Sunlight contains light (UV rays) Ultraviolet light has higher and shorter wavelengths than visible light. UV rays can pass through thin layers of clouds, causing. X rays and gamma rays are used in. Both have energy and short wavelengths than UV rays 4

5 Visible Light Spectrum Visible Spectrum we can see Roy G. Biv for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. Largest to Smallest Wavelength. rays have the highest energy and the shortest wavelengths. Both rays can kill living cells, or turn them into cells. Gamma rays can be used to treat, by killing diseased cells Infrared light can be felt as. Infrared light from the or a heat lamp warm you. Infrared light from heat lamps is used to keep warm. Remote sensors on weather read infrared light (temperature changes) for the tracking of movement Microwaves are used in and communication. Radar is a system that uses reflected radio waves to determine the distance to and the of objects stands for radio detection and ranging 16.3 Reflection and Color Reflection of Light Every object reflects some light and some light. Light can be modeled as a ray in the that light travels A light ray is a model of that represents light traveling through space in an imaginary straight line. Geometrical optics is the study of light in circumstances where behaves like a ray. Reflection Rough reflect light rays in many. Smooth surfaces reflect light in one direction. The angle of reflection is the light rays off the surface. The angle of incidence is the light rays the surface 5

6 Law of Reflection The Law of Reflection: the angle of equals the angle of Both angles are measured from a line that is to the surface at the point were the light hits the mirror (normal line) Mirrors Flat mirrors form images by reflection. A virtual image is an image that forms at a point from which light rays to come but do actually come. Some of the light rays are off the mirror into your eyes. Curved mirrors Can images The normal line points in different for different parts of a curved mirror. Convex mirrors Curve or bulge Produce a out image Light rays that start out parallel are reflected in different directions Make objects appear than they actually are Ex. Mirrors on the passenger side of vehicles Concave mirrors Indented mirrors; caved shape Create images AND images A real image results when light rays are focused a single point or small area Used to focus reflected light into a area used curved surfaces to focus light Radio telescopes gather radio waves from extremely objects; reflect off almost ay solid surface and thus do not need mirrors 6

7 Seeing Color Objects have color because they certain of light The that you perceive depend on the wavelengths of visible light that reach your Light through a prism separates into a of colors White light from the sun contains light from all the regions of the electromagnetic spectrum Colors may add or to produce other colors. Television and computer monitors display many colors by combining light of the primary colors, red, green, and blue Pigments, paints, or filters use primary colors yellow, cyan, and in a reverse process is the absence of color; all light is absorbed 16.4 Refraction, Lenses, and Prisms Refraction of Light Light waves bend, or refract, when they pass from one medium to another Refraction makes objects appear to be in positions of light in the atmosphere creates mirages. Light travels at slightly different speeds in air of different. (light refracted over hot asphalt) Light can be reflected at the between two transparent media Fiber optics use reflection. Total internal reflection is the complete of light at the boundary between two media when the angle of incidence exceeds the angle Lenses Lenses Rely on 7

8 A lens is a transparent object that refracts light rays, causing them to or to create an image A converging lens light inward (virtual or real image) A lens bends light (virtual image only) Lenses can images. Magnification is any change in size of an image compared with the size of the object. Refracting Telescopes and the Eye and refracting telescopes use multiple lenses. Refracting telescopes work more like a. Refracting focus light through several lenses. The eye depends on refraction and. The refracts 70% of the light in the eye. The of the lens determines how much further the lens refracts light. can adjust the curvature of the lens until an image is focused on the back layer of the eye, the When light strikes the rods and cones of the eye, signals are sent to the. Images are interpreted. A prism is a transparent block with a cross section. Different colors of light are differently. Light waves with wavelengths travel at different speeds. In the visible spectrum: slowest; -fastest The slower light more when passing between media Dispersion is an effect in which light separates into its colors. are caused by and reflection. 8