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Physics of Waves and Sound

The document discusses different types of waves including transverse waves, which involve side-to-side movements, and longitudinal waves, which involve backward and forward movements. It also describes key characteristics of waves like speed, frequency, wavelength, amplitude, and how the speed of a wave can be calculated using its frequency and wavelength. Specific types of waves covered include sound waves, which require a medium and cause our eardrums to vibrate, and light waves, which can travel through empty space. Reflection, refraction, and diffraction are described as common effects waves can experience.

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64 views4 pages

Physics of Waves and Sound

The document discusses different types of waves including transverse waves, which involve side-to-side movements, and longitudinal waves, which involve backward and forward movements. It also describes key characteristics of waves like speed, frequency, wavelength, amplitude, and how the speed of a wave can be calculated using its frequency and wavelength. Specific types of waves covered include sound waves, which require a medium and cause our eardrums to vibrate, and light waves, which can travel through empty space. Reflection, refraction, and diffraction are described as common effects waves can experience.

Uploaded by

camila
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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FYSICA

NOTA 2 PAG : 124 - 150

TRANSVERSE WAVES

- Side to side movements

- movements are called oscillations

LONGITUDINAL WAVES

- Sections are known as compressions and rare fractions

- movements of oscillations are backward and forwards

- example: sound waves

DESCRIBING WAVES

- Speed = m/s

- Frequency : number of waves passing any poit per second (Hz )

- Period: Time for one oscillation ( 1 / frequency )

- WaveLength: distance of wave

- Amplitude :

- Wave equation:

- speed = frequency * length

WAVE EFFECTS

- REFLECTION:
- Waves are reflected from the surface at the same angle as they strike it

- REFRACTION
- The wave slow and change direction

- DIFFRACTION
- The waves passes through a gap

- wider gaps produce less diffraction


- Sound bends around obstacules
SOUND WAVES

- When they reach your ear , they make your eardrums vibrate and your hear a sound

- caused by vibrations

- sound waves need a medium to travel through

- sound cannot travel through a vacuum

- can travel through solid liquid and gases

DISPLAYING SOUNDS

- Using a microscope and a oscilloscope

- The vibrations are changed into electrical ossilations.

- producing a waveform

- This is how pressure at the microscope varies with time.

SPEED OF SOUND AND ECHOES

- speed of sound : 330 ms

- The speed of sound depends on the temperature of air


- Travel faster through hot air

- Does not depend on the pressure of the air.

- The speed of sound is different through different materials.


- Travel faster through solids ( particles closer together)

MEASURING THE SPEED OF SOUND

SPEED = DISTANCE : TIME

REFRACTION OF SOUND

- Traffic in the night sounds louder


- ground cools down, waves leaving the ground tend to bend, instead of spreading up,
- Bending effect like this caused by speed is called refraction.
ECHOES

- Hard surfaces reflect sound waves


- Echo, you are hearing a reflected sound a short time after the original sound.

- Speed = 2 * distance to wall : echo time

- Echo - sounder: measures the depth of water under a boat

- Electronic tape measure : distance between 2 walls

- Radar : detects the position of aircraft.

CHARACTERISTICS OF SOUND WAVES


Frequency and pitch

- Sound waves are caused by vibrations

- The faster an object vibrates: the higher pitched the noise it makes.

- The bigger the vibrations when an object vibrates: The louder the sound it
makes.

- number of oscillations per second is called frequenzy

- measured in hertz

- Ear human : 20 up to 20 000

- 1 octave 64

WAVE EQUATION

SPEED = FREQUENCY * WAVE LENGTH

ULTRASOUND

- Sounds that are above the range of human hearing

LIGHT AND RAYS

- luminous objects and non luminous

- non luminous reflect light and some goes into your eyes

- paper : diffuse reflection


- mirror: regular reflection
- black surface : absorption
- glass : transmission
FEATURES OF LIGHT

- Light is a form of radiation ( spreads out )

- Light travels in straight line

- Light travels as waves

- Light transfers energy:

- Light can travel through empty space

- Light is the fastest thing their is

WAVE LENGTH AND COLOUR

- Most sources emit a mixture of wave length

- lasers emit light of a single wave length - monochromatic

REFLECTION IN PLANE MIRRORS


The laws of reflection

- Ray strikes a mirror:


- reflected
- incoming ray : incident ray
- outgoing ray : reflected
- normal ( line at right angle )

Laws of reflection:

- Angle of incidence is equal to the angle of reflection


- Incident ray , reflected ray and the normal lie all in the same place.

RULES FOR IMAGE SIZE AND POSITION


Plane mirror forms an image

- The image is the same size as the object

- The image size is as far behind the mirror s the object is in front

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