Hessa/tqa-multimodalContext-all · Datasets at Hugging Face

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L_0739	temperature and heat	T_3692	FIGURE 18.1 The cocoa is scalding hot. The bath water is comfortably warm. Why does the bath water have more thermal energy than the cocoa?	image	textbook_images/temperature_and_heat_22355.png
L_0739	temperature and heat	T_3694	FIGURE 18.2 The red liquid in this thermometer is alcohol. Alcohol expands uniformly over a wide range of temperatures. This makes it ideal for use in thermometers.	image	textbook_images/temperature_and_heat_22356.png
L_0739	temperature and heat	T_3695	FIGURE 18.3 A cool spoon gets warmer when it is placed in a hot liquid. Can you explain why?	image	textbook_images/temperature_and_heat_22357.png
L_0739	temperature and heat	T_3696	FIGURE 18.4 Sand on a beach heats up quickly in the sun because sand has a relatively low specific heat.	image	textbook_images/temperature_and_heat_22358.png
L_0740	transfer of thermal energy	T_3698	FIGURE 18.6 How is thermal energy transferred in each of these examples?	image	textbook_images/transfer_of_thermal_energy_22360.png
L_0740	transfer of thermal energy	T_3701	FIGURE 18.7 Thermal insulators have many practical uses. Can you think of others?	image	textbook_images/transfer_of_thermal_energy_22361.png
L_0740	transfer of thermal energy	T_3702	FIGURE 18.8 Convection currents carry thermal energy throughout the soup in the pot.	image	textbook_images/transfer_of_thermal_energy_22362.png
L_0740	transfer of thermal energy	T_3702	FIGURE 18.9 A sea breeze blows toward land during the day, and a land breeze blows toward water at night. Why does the wind change direction after the sun goes down?	image	textbook_images/transfer_of_thermal_energy_22363.png
L_0740	transfer of thermal energy	T_3703	FIGURE 18.10 Earth is warmed by energy that radiates from the sun. Earth radiates some of the energy back into space. Green- house gases (GHGs) trap much of the re- radiated energy, causing an increase in the temperature of the atmosphere close to the surface.	image	textbook_images/transfer_of_thermal_energy_22364.png
L_0740	transfer of thermal energy	DD_0212	This diagram shows convection currents. Convection is the transfer of heat from one place to another by the movement of fluids. The heat source lies at the bottom of the diagram. The heat generated by this source causes the air next to it, to warm up. Warm air is lighter than cool air, and hence it rises up. As it rises up, it moves away from the heat source and cools down. As it cools down, it gets heavier and sinks towards the heat source. This cycle continues and causes a convection current.	image	teaching_images/convection_of_air_8050.png
L_0740	transfer of thermal energy	DD_0213	This diagram shows the phenomena of the transfer of thermal energy. It happens by the convection of hot and cold air. The sun heats up the air, making it warm and less dense. Less dense air tends to go up, cooling down as doing it. Cool air becomes more dense and tends to sink, and wind does the job of making the air travel through different places, warming or cooling as he goes.	image	teaching_images/convection_of_air_6657.png
L_0741	using thermal energy	T_3705	FIGURE 18.12 When water is heated in the boiler, it expands. It might burst the pipes of the system if it werent for the expansion tank. This tank holds excess water after it ex- pands.	image	textbook_images/using_thermal_energy_22366.png
L_0741	using thermal energy	T_3706	FIGURE 18.13 The warm-air vent is placed near the floor of the room. Warm air is less dense than cold air so it rises. If the warm-air vent were placed near the ceiling instead, how would this affect the transfer of thermal energy throughout the room?	image	textbook_images/using_thermal_energy_22367.png
L_0741	using thermal energy	T_3708	FIGURE 18.14 A refrigerator must do work to reverse the normal direction of heat flow.	image	textbook_images/using_thermal_energy_22368.png
L_0741	using thermal energy	T_3710	FIGURE 18.15 Thermal energy is converted to the kinetic energy of the moving piston inside the cylinder. The moving piston, in turn, can be used to turn a turbine or do other useful work.	image	textbook_images/using_thermal_energy_22369.png
L_0742	characteristics of waves	T_3712	FIGURE 19.1 A drop of water causes a disturbance that travels through the pond as a wave.	image	textbook_images/characteristics_of_waves_22371.png
L_0742	characteristics of waves	T_3716	FIGURE 19.2 In a transverse wave, the medium moves at right angles to the direction of the wave.	image	textbook_images/characteristics_of_waves_22372.png
L_0742	characteristics of waves	T_3716	FIGURE 19.3 Crests and troughs are the high and low points of a transverse wave.	image	textbook_images/characteristics_of_waves_22373.png
L_0742	characteristics of waves	T_3716	FIGURE 19.4 An S wave is a transverse wave that trav- els through rocks under Earths surface.	image	textbook_images/characteristics_of_waves_22374.png
L_0742	characteristics of waves	T_3717	FIGURE 19.5 In a longitudinal wave, the medium moves back and forth in the same direction as the wave.	image	textbook_images/characteristics_of_waves_22375.png
L_0742	characteristics of waves	T_3719	FIGURE 19.6 The compressions and rarefactions of a longitudinal wave are like the crests and troughs of a transverse wave.	image	textbook_images/characteristics_of_waves_22376.png
L_0742	characteristics of waves	T_3719	FIGURE 19.7 P waves are longitudinal waves that travel through rocks under Earths surface.	image	textbook_images/characteristics_of_waves_22377.png
L_0742	characteristics of waves	T_3720	FIGURE 19.8 Surface waves are both transverse and longitudinal waves.	image	textbook_images/characteristics_of_waves_22378.png
L_0743	measuring waves	T_3721	FIGURE 19.11 Wave amplitude and wavelength are two important measures of wave size.	image	textbook_images/measuring_waves_22381.png
L_0743	measuring waves	T_3723	FIGURE 19.12 Both of these waves have the same ampli- tude, but they differ in wavelength. Which wave has more energy?	image	textbook_images/measuring_waves_22382.png
L_0743	measuring waves	T_3725	FIGURE 19.13 A transverse wave with a higher fre- quency has crests that are closer to- gether.	image	textbook_images/measuring_waves_22383.png
L_0743	measuring waves	DD_0214	The figure shows a transverse wave. In a transverse wave, wave amplitude is the height of each crest above the resting position. The higher the crests are, the greater the amplitude. Another important measure of wave size is wavelength. Wave amplitude is the maximum distance the particles of a medium move from their resting position when a wave passes through. The resting position (dotted line in the middle of the wave) is where the particles would be in the absence of a wave. Wavelength can be measured as the distance between two adjacent crests of a transverse wave. It is usually measured in meters. Wavelength is related to the energy of a wave. Short-wavelength waves have more energy than long-wavelength waves of the same amplitude.	image	teaching_images/waves_9296.png
L_0743	measuring waves	DD_0215	This diagram represents a sound wave and its characteristics. The peak of a wave is called compression or crest. The valley of a wave is called rarefaction or trough. Wave length is the length between two consecutive peaks, i.e. crest or two consecutive valleys, i.e. trough of a wave. Louder sound has shorter wavelength and softer sound has longer wavelength. Magnitude of maximum disturbance on either side of the normal position or mean value in a medium is called amplitude. In other words, amplitude is the distance from normal to the crest or trough. Time required to produce one complete wave is called time period or time taken to complete on oscillation is called the time period of the sound wave. The number of sound waves produced in unit time is called the frequency of sound waves. Frequency is the reciprocal of the time period of wave. Distance covered by sound wave in unit time is called the velocity of sound wave.	image	teaching_images/waves_7678.png
L_0744	wave interactions and interference	T_3730	FIGURE 19.14 This man is sending sound waves toward a rock wall so he can hear an echo.	image	textbook_images/wave_interactions_and_interference_22384.png
L_0744	wave interactions and interference	T_3730	FIGURE 19.15 Ocean waves are reflected by rocks on shore.	image	textbook_images/wave_interactions_and_interference_22385.png
L_0744	wave interactions and interference	T_3731	FIGURE 19.16 Waves strike a wall at an angle, called the angle of incidence. The waves are re- flected at the same angle, called the angle of reflection, but in a different direction. Both angles are measured relative to a line that is perpendicular to the wall.	image	textbook_images/wave_interactions_and_interference_22386.png
L_0744	wave interactions and interference	T_3731	FIGURE 19.17 This pencil looks broken where it enters the water because of refraction of light waves.	image	textbook_images/wave_interactions_and_interference_22387.png
L_0744	wave interactions and interference	T_3732	FIGURE 19.18 The person can hear the radio around the corner of the building because of the diffraction of sound waves.	image	textbook_images/wave_interactions_and_interference_22388.png
L_0744	wave interactions and interference	T_3732	FIGURE 19.19 An obstacle or opening that is shorter than the wavelength causes greater diffraction of waves.	image	textbook_images/wave_interactions_and_interference_22389.png
L_0744	wave interactions and interference	T_3734	FIGURE 19.20 Constructive interference increases wave amplitude.	image	textbook_images/wave_interactions_and_interference_22390.png
L_0744	wave interactions and interference	T_3736	FIGURE 19.21 Destructive interference decreases wave amplitude.	image	textbook_images/wave_interactions_and_interference_22391.png
L_0748	characteristics of sound	T_3770	FIGURE 20.1 This tree cracked and fell to the ground in a storm. Can you imagine what it sounded like when it came crashing down?	image	textbook_images/characteristics_of_sound_22407.png
L_0748	characteristics of sound	T_3771	FIGURE 20.2 Plucking a guitar string makes it vibrate. The vibrating string sends sound waves through the air in all directions.	image	textbook_images/characteristics_of_sound_22408.png
L_0748	characteristics of sound	T_3775	FIGURE 20.3 High-decibel sounds can damage the ears and cause loss of hearing. Which sounds in the graph are dangerously loud?	image	textbook_images/characteristics_of_sound_22409.png
L_0748	characteristics of sound	T_3775	FIGURE 20.4 The energy of sound waves spreads out over a greater area as the waves travel farther from the sound source. This di- agram represents just a small section of the total area of sound waves spreading out from the source. Sound waves ac- tually travel away from the source in all directions. As distance from the source increases, the area covered by the sound waves increases, lessening their inten- sity.	image	textbook_images/characteristics_of_sound_22410.png
L_0748	characteristics of sound	T_3776	FIGURE 20.5 A piccolo and a tuba sound very differ- ent. One difference is the pitch of their sounds.	image	textbook_images/characteristics_of_sound_22411.png
L_0748	characteristics of sound	T_3777	FIGURE 20.6 The sirens pitch changes as the police car zooms by. Can you explain why?	image	textbook_images/characteristics_of_sound_22412.png
L_0749	hearing sound	T_3779	FIGURE 20.7 The three main parts of the ear have different functions in hearing.	image	textbook_images/hearing_sound_22413.png
L_0749	hearing sound	T_3782	FIGURE 20.8 This highly magnified image of a hair cell shows the tiny hair-like structures on its surface. What function do the "hairs" play in hearing?	image	textbook_images/hearing_sound_22414.png
L_0749	hearing sound	T_3782	FIGURE 20.9 The louder the sounds are, the less time you should be exposed to them for the sake of your hearing.	image	textbook_images/hearing_sound_22415.png
L_0750	using sound	T_3786	FIGURE 20.12 A drum, saxophone, and violin represent the three basic categories of musical in- struments. Can you name other instru- ments in each category?	image	textbook_images/using_sound_22418.png
L_0750	using sound	T_3789	FIGURE 20.13 Bats use ultrasound to find prey.	image	textbook_images/using_sound_22419.png
L_0750	using sound	T_3790	FIGURE 20.14 Sonar works on the same principle as echolocation.	image	textbook_images/using_sound_22420.png
L_0750	using sound	T_3791	FIGURE 20.15 This ultrasound image shows an unborn baby inside its mothers body. Do you see the babys face?	image	textbook_images/using_sound_22421.png
L_0751	electromagnetic waves	T_3793	FIGURE 21.1 Magnetic and electric fields are invisible areas of force surrounding magnets and charged particles. The field lines in the diagrams represent the direction and location of the force.	image	textbook_images/electromagnetic_waves_22422.png
L_0751	electromagnetic waves	T_3794	FIGURE 21.2 An electromagnetic wave starts with a vibrating charged particle.	image	textbook_images/electromagnetic_waves_22423.png
L_0751	electromagnetic waves	T_3798	FIGURE 21.3 A photon of light energy is given off when an electron returns to a lower energy level.	image	textbook_images/electromagnetic_waves_22424.png
L_0752	properties of electromagnetic waves	T_3800	FIGURE 21.4 Light slows down when it enters water from the air. This causes the wave to refract, or bend.	image	textbook_images/properties_of_electromagnetic_waves_22425.png
L_0752	properties of electromagnetic waves	T_3802	FIGURE 21.5 Wavelength and frequency of electromagnetic waves.	image	textbook_images/properties_of_electromagnetic_waves_22426.png
L_0753	the electromagnetic spectrum	T_3804	FIGURE 21.6 Electromagnetic radiation from the sun reaches Earth across space. It strikes everything on Earths surface, including these volleyball players.	image	textbook_images/the_electromagnetic_spectrum_22427.png
L_0753	the electromagnetic spectrum	T_3804	FIGURE 21.7 How do the wavelength and frequency of waves change across the electromagnetic spectrum?	image	textbook_images/the_electromagnetic_spectrum_22428.png
L_0753	the electromagnetic spectrum	T_3806	FIGURE 21.8 AM radio waves reflect off the ionosphere and travel back to Earth. Radio waves used for FM radio and television pass through the ionosphere and do not reflect back.	image	textbook_images/the_electromagnetic_spectrum_22429.png
L_0753	the electromagnetic spectrum	T_3807	FIGURE 21.9 This television tower broadcasts signals using radio waves.	image	textbook_images/the_electromagnetic_spectrum_22430.png
L_0753	the electromagnetic spectrum	T_3810	FIGURE 21.10 Microwaves are used for cell phones and radar. MEDIA Click image to the left or use the URL below. URL: https://www.ck12.org/flx/render/embeddedobject/5050	image	textbook_images/the_electromagnetic_spectrum_22431.png
L_0753	the electromagnetic spectrum	T_3810	FIGURE 21.11 Red light (right) has the longest wave- length, and violet light (left) has the short- est wavelength.	image	textbook_images/the_electromagnetic_spectrum_22432.png
L_0753	the electromagnetic spectrum	T_3812	FIGURE 21.12 This sterilizer for laboratory equipment uses ultraviolet light to kill bacteria.	image	textbook_images/the_electromagnetic_spectrum_22433.png
L_0753	the electromagnetic spectrum	T_3813	FIGURE 21.13 If your skin normally burns in 10 minutes of sun exposure, using sunscreen with an SPF of 30 means that, ideally, your skin will burn only after 30 times 10 minutes, or 300 minutes, of sun exposure. How long does sunscreen with an SPF of 50 protect skin from sunburn?	image	textbook_images/the_electromagnetic_spectrum_22434.png
L_0753	the electromagnetic spectrum	T_3814	FIGURE 21.14 Two common uses of X rays are illustrated here.	image	textbook_images/the_electromagnetic_spectrum_22435.png
L_0753	the electromagnetic spectrum	DD_0216	This diagram shows light waves of varying lengths, and some of their characteristics. The red line illustrates the wavelengths. Above that is a bar showing which light waves penetrate the Earth's atmosphere. Below the red line are the names of the different types of light, with their wavelength measured in (m). The illustrations of physical objects are to show scale. Below that is a diagram of the different light frequencies, measured in Hertz. Below that is a measure of the temperatures at which these light waves are most commonly emitted.	image	teaching_images/em_spectrum_6818.png
L_0753	the electromagnetic spectrum	DD_0217	The diagram shows different kinds of waves. Visible light is the part of the electromagnetic spectrum that humans can see. Visible light includes all the colors of the rainbow. Each color is determined by its wavelength. Visible light ranges from violet wavelengths of 400 nanometers (nm) through red at 700 nm. There are parts of the electromagnetic spectrum that humans cannot see. This radiation exists all around you. You just cant see it! Every star, including our Sun, emits radiation of many wavelengths. Astronomers can learn a lot from studying the details of the spectrum of radiation from a star. Many extremely interesting objects cant be seen with the unaided eye.	image	teaching_images/em_spectrum_9095.png
L_0754	the light we see	T_3817	FIGURE 22.1 This classroom has two obvious sources of visible light. Can you identify all of them?	image	textbook_images/the_light_we_see_22436.png
L_0754	the light we see	T_3818	FIGURE 22.2 Bioluminescent organisms include jelly- fish and fireflies. Jellyfish give off visible light to startle predators. Fireflies give off visible light to attract mates.	image	textbook_images/the_light_we_see_22437.png
L_0754	the light we see	T_3825	FIGURE 22.3 The objects pictured here differ in the way light interacts with them.	image	textbook_images/the_light_we_see_22438.png
L_0754	the light we see	T_3826	FIGURE 22.4 The color of light depends on its wave- length.	image	textbook_images/the_light_we_see_22439.png
L_0754	the light we see	T_3826	FIGURE 22.5 A prism separates visible light into its different wavelengths.	image	textbook_images/the_light_we_see_22440.png
L_0754	the light we see	T_3826	FIGURE 22.6 The color that objects appear depends on the wavelengths of light they reflect or transmit.	image	textbook_images/the_light_we_see_22441.png
L_0754	the light we see	T_3826	FIGURE 22.7 The three primary colors of lightred, green, and bluecombine to form white light in the center of the figure. What are the secondary colors of light? Can you find them in the diagram?	image	textbook_images/the_light_we_see_22442.png
L_0754	the light we see	T_3827	FIGURE 22.8 Printer ink comes in three primary pig- ment colors: cyan, magenta, and yellow.	image	textbook_images/the_light_we_see_22443.png
L_0755	optics	T_3829	FIGURE 22.9 Still waters of a lake create a mirror image of the surrounding scenery.	image	textbook_images/optics_22444.png
L_0755	optics	T_3830	FIGURE 22.10 Whether reflection is regular or diffuse de- pends on the smoothness of the reflective surface.	image	textbook_images/optics_22445.png
L_0755	optics	T_3831	FIGURE 22.11 According to the law of reflection, the an- gle of reflection always equals the angle of incidence. The angles of both reflected and incident light are measured relative to an imaginary line, called normal, that is perpendicular (at right angles) to the reflective surface.	image	textbook_images/optics_22446.png
L_0755	optics	T_3834	FIGURE 22.12 The term mirror image refers to how left and right are reversed in the image compared with the real object.	image	textbook_images/optics_22447.png
L_0755	optics	T_3834	FIGURE 22.13 The image created by a concave mirror depends on how far the object is from the mirror.	image	textbook_images/optics_22448.png
L_0755	optics	T_3836	FIGURE 22.14 A convex mirror forms a virtual image that appears to be on the opposite side of the mirror from the object. How is the image different from the object?	image	textbook_images/optics_22449.png
L_0755	optics	T_3836	FIGURE 22.15 Light refracts when it passes from one medium to another at an angle other than 90 . Can you explain why?	image	textbook_images/optics_22450.png
L_0755	optics	T_3838	FIGURE 22.16 The image formed by a concave lens is a virtual image.	image	textbook_images/optics_22451.png
L_0755	optics	T_3841	FIGURE 22.17 The type of image made by a convex lens depends on how close the object is to the lens. Which diagram shows how a hand lens makes an image?	image	textbook_images/optics_22452.png
L_0755	optics	T_3841	FIGURE 22.18 A compound microscope uses convex lenses to make enlarged images of tiny objects.	image	textbook_images/optics_22453.png
L_0755	optics	T_3843	FIGURE 22.19 These telescopes differ in how they collect light, but both use convex lenses to enlarge the image.	image	textbook_images/optics_22454.png
L_0755	optics	T_3843	FIGURE 22.20 A camera uses a convex lens to form an image on film or a sensor.	image	textbook_images/optics_22455.png
L_0755	optics	T_3844	FIGURE 22.21 A very focused beam of bright laser light moves around the room for the cat to chase. The diagram shows why the beam of laser light is so focused compared with ordinary light from a flashlight.	image	textbook_images/optics_22456.png
L_0755	optics	T_3844	FIGURE 22.22 A laser light uses two concave mirrors to focus photons of colored light.	image	textbook_images/optics_22457.png
L_0755	optics	DD_0218	This diagram explains the concept of refraction. Light travels at a constant speed in vaccuum but travels at different speends in different media. When light travels from one medium to another, the speed of light changes causing it to appear to bend. This bending of light is called refraction. Refraction occurs when the angle of incidence (i) is not 90 degrees. In this diagram (r) is the angle of refraction. The angle of refraction is dependent on the angle o incidence as well as the speed of light in the medium through which it is travelling. XY is the boundary between the media through which light is travelling. At the point of incidence where the ray strikes the boundary XY, a line can be drawn perpendicular to XY. This line is known as a normal line (labeled NN' in the diagram) .	image	teaching_images/optics_refraction_9190.png
L_0755	optics	DD_0219	This diagram shows the setup of an amateur reflecting telescope. The telescope tube sits on a movable mount that allows it to point at and track objects in the sky. The mount shown is equitorial, meaning that it can be aligned to the north star for easier tracking of other stars and planets as they move accross the sky. The mount has a counterweight to help balance the wieght of the telescope tube. The entire assembly sits on the three legs of a tripod. When pointed at the sky, light enters the optical tube through it's aperture. The aperture is the circular end of the tube that allows light to enter when uncovered. Once light has entered the telescope, it is gathered and directed to the eyepiece by mirrors. The lenses in the eyepeice take this light and bring an image to focus for a human to see. The finderscope is a second smaller telescope attached the optical tube. It has lower magnification than the telescope, and this makes finding onjects and pointing the telescope easier.	image	teaching_images/parts_telescope_8149.png
L_0755	optics	DD_0220	This diagram explains the law of reflection and shows how light gets reflected from a surface. The law of reflection states that the angle of incidence (i) is always equal to the angle of reflection (r). The angles of both reflected and incident ray are measured relative to the imaginary dotted-line, called normal, that is perpendicular (at right angles) to the mirror (reflective surface). On the other hand, Refraction is caused by the change in speed experienced by a wave when it changes medium. The refracted ray is a ray (drawn perpendicular to the wave fronts) that shows the direction that light travels after it has crossed over the boundary. The angle that the incident ray makes with the normal line is referred to as the angle of incidence. Similarly, the angle that the refracted ray makes with the normal line is referred to as the angle of refraction. Thus, this is what the following diagram is all about.	image	teaching_images/optics_refraction_9200.png
L_0755	optics	DD_0221	The diagram below is about two different types of lens. A lens is a transparent piece of glass or plastic with at least one curved surface. A lens works by refraction: it bends light rays as they pass through it so they change direction. In a convex lens (sometimes called a positive lens), the glass (or plastic) surfaces bulge outwards in the center giving the classic lentil-like shape. A convex lens is also called a converging lens because it makes parallel light rays passing through it bend inward and meet (converge) at a spot just beyond the lens known as the focal point Convex lenses are used in things like telescopes and binoculars to bring distant light rays to a focus in your eyes. A concave lens is exactly the opposite with the outer surfaces curving inward, so it makes parallel light rays curve outward or diverge. That's why concave lenses are sometimes called diverging lenses. (One easy way to remember the difference between concave and convex lenses is to think of concave lenses caving inwards). Concave lenses are used in things like TV projectors to make light rays spread out into the distance.	image	teaching_images/optics_lense_types_9163.png
L_0755	optics	DD_0222	This diagram shows the arrangement of optics found in a refracting telescope. Llight entering the telescope first encounters the large objective lens placed a the telescopes aperure the optical tube through it's aperture, a circular opening at the forward end of the tube. The objective lens is convex, and it causes rays of light entered the telescope parallel to one another to converge. The eyepiece lens is located in the path of these converging rays, and brings an image to focus for the human eye.	image	teaching_images/parts_telescope_8156.png
L_0755	optics	DD_0223	This Diagrams shows the different types of lenses. A lens is a clear (transparent) object (like glass, plastic or even a drop of water) that changes the way things look by bending the light that goes through it. They may make things appear larger, smaller, or upside-down. Lenses are classified by the curvature of the two optical surfaces. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. If both surfaces have the same radius of curvature, the lens is equiconvex. A lens with two concave surfaces is biconcave (or just concave). If one of the surfaces is flat, the lens is plano-convex or plano-concave depending on the curvature of the other surface. A lens with one convex and one concave side is convex-concave or meniscus. It is this type of lens that is most commonly used in corrective lenses. If the lens is biconvex or plano-convex, a collimated beam of light passing through the lens converges to a spot (a focus) behind the lens. In this case, the lens is called a positive or converging lens.	image	teaching_images/optics_lense_types_9159.png
L_0755	optics	DD_0224	This diagram shows the arrangement of optics found in a reflecting telescope. Light enters the optical tube through it's aperture, a circular opening at the forward end of the tube. When light enters the telescope, it encounters a concave reflecting mirror at the back of telescope tube. This large reflecting mirror is called the objective. Light reflected from the objective converges on a small right angle mirror at the center of the optical tube. This mirror reflects the gathered light to the eyepiece. The lenses in the eyepeice take this light and bring an image to focus for a human to see.	image	teaching_images/parts_telescope_8153.png
L_0756	vision	T_3845	FIGURE 22.24 The human eye is the organ specialized to collect light and focus images. Structures of the Eye	image	textbook_images/vision_22459.png
L_0756	vision	T_3846	FIGURE 22.25 The brain and eyes work together to allow us to see.	image	textbook_images/vision_22460.png
L_0756	vision	T_3847	FIGURE 22.26 Myopia and hyperopia can be corrected with lenses.	image	textbook_images/vision_22461.png
L_0761	magnets and magnetism	T_3883	FIGURE 24.2 The north and south poles of a bar magnet attract paper clips.	image	textbook_images/magnets_and_magnetism_22485.png
L_0761	magnets and magnetism	T_3886	FIGURE 24.3 Lines of magnetic force are revealed by the iron filings attracted to this magnet.	image	textbook_images/magnets_and_magnetism_22486.png
L_0761	magnets and magnetism	T_3887	FIGURE 24.4 When it come to magnets, there is a force of attraction between opposite poles and a force of repulsion between like poles.	image	textbook_images/magnets_and_magnetism_22487.png

L_0739

temperature and heat

T_3692

FIGURE 18.1 The cocoa is scalding hot. The bath water is comfortably warm. Why does the bath water have more thermal energy than the cocoa?

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textbook_images/temperature_and_heat_22355.png

L_0739

temperature and heat

T_3694

FIGURE 18.2 The red liquid in this thermometer is alcohol. Alcohol expands uniformly over a wide range of temperatures. This makes it ideal for use in thermometers.

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textbook_images/temperature_and_heat_22356.png

L_0739

temperature and heat

T_3695

FIGURE 18.3 A cool spoon gets warmer when it is placed in a hot liquid. Can you explain why?

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textbook_images/temperature_and_heat_22357.png

L_0739

temperature and heat

T_3696

FIGURE 18.4 Sand on a beach heats up quickly in the sun because sand has a relatively low specific heat.

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transfer of thermal energy

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FIGURE 18.6 How is thermal energy transferred in each of these examples?

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transfer of thermal energy

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FIGURE 18.7 Thermal insulators have many practical uses. Can you think of others?

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transfer of thermal energy

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FIGURE 18.8 Convection currents carry thermal energy throughout the soup in the pot.

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transfer of thermal energy

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FIGURE 18.9 A sea breeze blows toward land during the day, and a land breeze blows toward water at night. Why does the wind change direction after the sun goes down?

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transfer of thermal energy

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FIGURE 18.10 Earth is warmed by energy that radiates from the sun. Earth radiates some of the energy back into space. Green- house gases (GHGs) trap much of the re- radiated energy, causing an increase in the temperature of the atmosphere close to the surface.

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transfer of thermal energy

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This diagram shows convection currents. Convection is the transfer of heat from one place to another by the movement of fluids. The heat source lies at the bottom of the diagram. The heat generated by this source causes the air next to it, to warm up. Warm air is lighter than cool air, and hence it rises up. As it rises up, it moves away from the heat source and cools down. As it cools down, it gets heavier and sinks towards the heat source. This cycle continues and causes a convection current.

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transfer of thermal energy

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This diagram shows the phenomena of the transfer of thermal energy. It happens by the convection of hot and cold air. The sun heats up the air, making it warm and less dense. Less dense air tends to go up, cooling down as doing it. Cool air becomes more dense and tends to sink, and wind does the job of making the air travel through different places, warming or cooling as he goes.

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using thermal energy

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FIGURE 18.12 When water is heated in the boiler, it expands. It might burst the pipes of the system if it werent for the expansion tank. This tank holds excess water after it ex- pands.

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using thermal energy

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FIGURE 18.13 The warm-air vent is placed near the floor of the room. Warm air is less dense than cold air so it rises. If the warm-air vent were placed near the ceiling instead, how would this affect the transfer of thermal energy throughout the room?

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using thermal energy

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FIGURE 18.14 A refrigerator must do work to reverse the normal direction of heat flow.

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using thermal energy

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FIGURE 18.15 Thermal energy is converted to the kinetic energy of the moving piston inside the cylinder. The moving piston, in turn, can be used to turn a turbine or do other useful work.

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characteristics of waves

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FIGURE 19.1 A drop of water causes a disturbance that travels through the pond as a wave.

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characteristics of waves

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FIGURE 19.2 In a transverse wave, the medium moves at right angles to the direction of the wave.

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characteristics of waves

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FIGURE 19.3 Crests and troughs are the high and low points of a transverse wave.

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characteristics of waves

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FIGURE 19.4 An S wave is a transverse wave that trav- els through rocks under Earths surface.

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characteristics of waves

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FIGURE 19.5 In a longitudinal wave, the medium moves back and forth in the same direction as the wave.

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characteristics of waves

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FIGURE 19.6 The compressions and rarefactions of a longitudinal wave are like the crests and troughs of a transverse wave.

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characteristics of waves

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FIGURE 19.7 P waves are longitudinal waves that travel through rocks under Earths surface.

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characteristics of waves

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FIGURE 19.8 Surface waves are both transverse and longitudinal waves.

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measuring waves

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FIGURE 19.11 Wave amplitude and wavelength are two important measures of wave size.

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measuring waves

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FIGURE 19.12 Both of these waves have the same ampli- tude, but they differ in wavelength. Which wave has more energy?

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measuring waves

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FIGURE 19.13 A transverse wave with a higher fre- quency has crests that are closer to- gether.

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measuring waves

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The figure shows a transverse wave. In a transverse wave, wave amplitude is the height of each crest above the resting position. The higher the crests are, the greater the amplitude. Another important measure of wave size is wavelength. Wave amplitude is the maximum distance the particles of a medium move from their resting position when a wave passes through. The resting position (dotted line in the middle of the wave) is where the particles would be in the absence of a wave. Wavelength can be measured as the distance between two adjacent crests of a transverse wave. It is usually measured in meters. Wavelength is related to the energy of a wave. Short-wavelength waves have more energy than long-wavelength waves of the same amplitude.

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measuring waves

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This diagram represents a sound wave and its characteristics. The peak of a wave is called compression or crest. The valley of a wave is called rarefaction or trough. Wave length is the length between two consecutive peaks, i.e. crest or two consecutive valleys, i.e. trough of a wave. Louder sound has shorter wavelength and softer sound has longer wavelength. Magnitude of maximum disturbance on either side of the normal position or mean value in a medium is called amplitude. In other words, amplitude is the distance from normal to the crest or trough. Time required to produce one complete wave is called time period or time taken to complete on oscillation is called the time period of the sound wave. The number of sound waves produced in unit time is called the frequency of sound waves. Frequency is the reciprocal of the time period of wave. Distance covered by sound wave in unit time is called the velocity of sound wave.

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