A reflected wave has less energy than the original wave.
Sound waves
- Sound is produced by the energy of vibrating objects.
- Sound waves are a series of compressions and refractions
- Sound waves travel through gases, liquids and solids by causing the particles to vibrate and thus cause our eardrums to vibrate.
- Sound waves move faster in solids than gases because the particles are held together in solids.
- Reflected sound is called an echo.
- Sound travels at different spreads In air of different temperatures. This may cause sound waves to be bent of refracted.
- Sonar is the use of sound waves and threw reflection to find the depth of the water.
Differences
- High pitch is squeaky sound with a short wavelength and high frequency.
- low pitch is gruff and have long wavelength but low frequency
- a soprano singer has a high pitched voice baritone has low pitched
An oscilloscope lets us see the electrical signals generated by the sound wave.
Music and Noise
- Music is pleasant, noise is an annoying sound.
- Ensemble is a group of musicians playing together.
- Orchestra is a very large group of musicians playing instruments together.
Music is made by vibrating either of the following:
- Strings
- Air
- Flap
- Resonance is when the waves from one vibrating object cause another to vibrate.
USES of SOUND:
- Supersonic is anything that travels faster than the speed of sound.
- Ultrasonic are sounds above the range of human hearing
- Ultrasound are higher frequency waves
- Ultrasounds are waves below the range of human hearing.
Electromagnetic Waves
- Electromagnetic waves can travel where there are no particles or substances
- They are made of oscillating (regularly vibrating) electric and magnetic fields.
- They are transverse waves.
- Formed by changes in atoms.
- When atoms gain energy, they absorb it and re-emit it as electric magnetic energy.
- Packets of energy are called protons
- Light all travels at the same speed of 35/08 m/s
- Light differs in wavelengths and frequency.
- As the wavelengths get shorter, the frequency gets higher.
- The range of all electromagnetic waves is called a spectrum
Types of RAYS
Gamma = shortest wavelength, very penetrating and dangerous, damages body
X-ray = Not visible directly, are absorbed more by bone than soft tissue cells.
Ultra-violet = Not visible to humans, but visible to insects, absorbed by the Earths ozone layer and causes sunburns and skin cancer.
Light = AKA visible light, only visible part of spectrum that our eyes can detect, provides all energy needed to maintain life on earth.
Infrared = we can feel them as heat, AKA heat radiation.
Mirrors
- Light beams and rays always travel in straight lines.
- A ray is a thin beam or strip of light whereas a wave is a movement of light.
Using lenses
- A lens is a piece of glass or plastic with curved sides.
- Convex and concave
- Look for diagram with focal length.
Color
- Special 'cone' cells at the back of our eyes detect different wavelengths of light.
- A rainbow is a color spectrum in the sky formed by the sun shining on water droplets.
- The spectrum of light into its colors is called dispersion.
- White light is a combination of all colors.
- A filter is a plastic sheet that absorbs some colors but lets others pass.
Reflection and Refraction
- Light that is not reflected is absorbed
- When light hits a smooth surface and bounces regularly, it is called regular reflection.
- When light hits a rough surface and separates, it is called diffuse reflection.
- Regular refraction is when light passes through an object that same direction it hit it.
- Diffuse refraction is when light hits an object regularly but leaves facing different directions.
- Translucent objects are those that let light pass through but do not allow us to see. Transparent objects let light pass through while also letting us see through.
Nature of Light
- Colors of light differ in wavelength
- Interference of light is when light cancels each other or adds up.
- Laser light is the only light made up of one wavelength.
- Polarization of light is when all light waves move in the same orientation
- The photoelectric effect is when light acts as a stream of particles.
- Light has a "double personality": waves of light, and streams of particles.
Waves and Technology
- Photonics is the use of light in electronic applications
- Infrared radiation measures changes on the earths surface
Medical Use
-
Ultrasound = The use of sound to produce a picture of the internal body
-
Scattering = the physical process which particles are deflected haphazardly as a result of collisions.
- X-Rays can be used to kill cancer cells to stop their spread.
SOS FORMULA
Speed of sound = Frequency X Wavelength