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Understanding Light and Sound: Properties, Innovations, and Applications in Technology

Explore the properties of light and sound waves, their role in communication, navigation, medicine, and entertainment, and innovations like LEDs, lasers, and soundproofing technologies.

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grade 11 - general science Light SOUN AND UNDERSTANDING AND USING LIGHTS AND SOUNDS
Light SOUN D LESSON OBJECTIVES: Discuss the properties of light and sound waves related to communications technology, navigation, medicine, and entertainment. Identify innovations related to sound and light, such as soundproofing, sound amplifiers, LEDs, AT THE END OF THE LESSON, YOU SHOULD BE ABLE TO: AND
think about it! IMAGINE A WORLD WITHOUT... GUIDE QUESTIONS: • WHAT DO THESE THINGS HAVE IN COMMON? • HOW DO LIGHT AND SOUND MAKE THEM POSSIBLE? CELLPHO NE MUSI C TRAFFIC LIGHTS ULTRASOUND MACHINES
What is Light? LIGHT IS A FORM OF ELECTROMAGNETIC ENERGY THAT TRAVELS IN WAVES. PROPERTIES OF LIGHT TRAVELS VERY FAST 300,000 KM/S TRAVELS IN STRAIGHT LINES CAN BE REFLECTED, REFRACTED, ABSORBED, AND SCATTERED DOES NOT NEED A MEDIUM TO TRAVEL. Light SOUN D AND
Properties of Light? REFLECTI ON Reflection occurs when light strikes a surface and bounces back. Examples: Mirror , Calm water , Polished metal Law of Reflection θi​ =θr​ ​ where: θi​= angle of incidence θr​= angle of reflection Light SOUN D AND
Properties of Light? REFLECTI ON Light SOUN D AND Two types of reflection 1. Regular reflection Occurs on a smooth surface. Reflected rays remain organized. Produces a clear image. Example: Plane mirror 2. Diffuse reflection Occurs on a rough surface. Light is scattered in different directions. Example: Paper or a rough wall.
Properties of Light? REFRACTI ON Refraction is the bending of light when it passes from one medium to another because its speed changes. For example: Air → Water Light changes speed and changes direction. Light SOUN D AND
Properties of Light? REFRACTI ON Examples of refraction • A pencil appears bent when placed in water. • Eyeglasses use refraction. • Lenses in cameras use refraction. • A swimming pool can appear shallower than it actually is. Important idea When light enters a different medium: Its speed can change, and its direction can change. Light SOUN D AND
Properties of Light? DIFFRACTI ON Diffraction is the bending or spreading of waves when they pass through a narrow opening or around an obstacle. Light can spread when it passes through a very small slit. Diffraction becomes more noticeable when the size of the opening is comparable to the wavelength of the light. Light SOUN D AND
Properties of Light? INTERFERE NCE Interference occurs when two or more light waves overlap. The waves can combine to produce: Constructive interference Waves combine to produce a larger amplitude. Destructive interference Waves combine and partially or completely cancel each other. Light SOUN D AND
Properties of Light? INTERFERE NCE Light SOUN D AND Soap bubbles show both constructive and destructive interference. As light hits the thin soap film, part of it reflects off the outer surface and part reflects off the inner surface. These light waves overlap, reinforcing some colors (constructive) and canceling others (destructive) to create shifting rainbow patterns.
Properties of Light? POLARIZATI ON Polarization is the process in which the vibrations of light are restricted to a particular direction. Normally, unpolarized light vibrates in many directions perpendicular to its direction of travel. When it passes through a polarizing filter, only vibrations in one direction are allowed to pass. Light SOUN D AND
Properties of Light? DISPERSIO N Dispersion occurs when white light separates into its different colors. A familiar example is a rainbow. White light contains different wavelengths, including: Red → Orange → Yellow → Green → Blue → Indigo → Violet A prism can separate white light into these colors. Light SOUN D AND
Properties of Light? DISPERSIO N Why does dispersion happen? Different colors of light travel at slightly different speeds in a material. Therefore, they bend by different amounts when passing through the material. Violet generally bends more than red in glass. Light SOUN D AND
Properties of Light? SCATTERIN G Scattering is the process in which light is redirected in different directions when it interacts with particles or molecules in a medium. Light SOUN D AND
Properties of Light? SCATTERIN G Why is the Sky Blue? The blue color of the daytime sky is mainly due to Rayleigh scattering. Sunlight contains many colors. When sunlight enters Earth's atmosphere, tiny gas molecules scatter the shorter wavelengths more strongly than the longer wavelengths. Light SOUN D AND
Properties of Light? SCATTERIN G Blue and violet light are scattered more strongly than red light. Although violet is scattered even more strongly, our eyes are more sensitive to blue, and some violet light is absorbed in the upper atmosphere. Therefore, we generally see the sky as blue. Light SOUN D AND
What is Sound? SOUND IS A MECHANICAL WAVE PRODUCED BY VIBRATING OBJECTS. UNLIKE LIGHT, SOUND NEEDS A MEDIUM TO TRAVEL. AI R WATE R SOLID S Light SOUN D AND
What is Sound? SOUND IS A MECHANICAL WAVE PRODUCED BY VIBRATING OBJECTS. UNLIKE LIGHT, SOUND NEEDS A MEDIUM TO TRAVEL. AI R WATE R SOLID S Light SOUN D AND
CHARACTERISTICS OF SOUND FREQUENC Y Frequency is the number of complete vibrations or cycles produced per second. The unit is hertz (Hz). f=time/number of cycles​ Example If a sound source vibrates 500 times per second: f=500 Hz Light SOUN D AND
CHARACTERISTICS OF SOUND PITCH Pitch describes how high or low a sound seems. Pitch depends primarily on frequency. Example A whistle generally produces a high-pitched sound, while a bass drum produces a low- pitched sound. Light SOUN D AND
CHARACTERISTICS OF SOUND SPEED The speed of sound is how fast the sound wave travels through a medium. The basic wave equation is: v=fλ​ where: v = wave speed (m/s) f = frequency (Hz) λ = wavelength (m) Light SOUN D AND
CHARACTERISTICS OF SOUND SPEED Important: Sound generally travels: fastest in solids → slower in liquids → slowest in gases Light SOUN D AND
CHARACTERISTICS OF SOUND WAVELENG TH Wavelength is the distance between two corresponding points of a wave. For a longitudinal sound wave, it can be measured from: compression → compression or rarefaction → rarefaction The symbol is: λ and the unit is meter (m). Light SOUN D AND
CHARACTERISTICS OF SOUND AMPLITUDE Amplitude is the maximum displacement of a vibrating particle from its equilibrium position. A larger amplitude means the sound wave carries more energy. Amplitude is related to Sound Larger amplitude → louder sound Smaller amplitude → softer sound Light SOUN D AND
CHARACTERISTICS OF SOUND LOUDNESS Loudness is how strong or soft a sound appears to our ears. It is related mainly to the amplitude and intensity of the sound wave. Sound level is commonly expressed in decibels (dB). Light SOUN D AND
Light Sound Electromagnetic wave Mechanical wave Travels in vacuum Needs a medium Faster Slower Can be reflected and refracted Can also reflect (echo) Used for vision Used for hearing COMPARING LIGHT AND SOUND
REFLECTION QUESTION Why can't astronauts hear each other directly in outer space?
INNOVATIONS USING LIGHT LED LIGHTS HOLOGRA MS LASE RS • Energy efficient • Longer lifespan • 3D images • Security features • Entertainment • Medicine • Manufacturing • Barcode scanners • Fiber optics
INNOVATIONS USING SOUND SOUND AMPLIFIERS SOUNDPROO FING • Recording studios • Hospitals • Classrooms • Speakers • Hearing aids • Concert systems
grade 11 - general science Light SOUN AND EXPLORING THE SCIENCE BEHIND EVERYDAY TECHNOLOGY