Waves

A cura della 4 A L.S. Docente: Lucia Russo

A wave is an oscillation accompanied by a transfer of energy, but not substance, that travels through space or mass.

An example of wave is the drop of water that falls into a puddle - it produces a circular ripple.

Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level PHISICAL QUANTITIES LINKED TO WAVES: Wavelength: spatial period of the wave. It is the distance between two crests or two troughs. The crest is the point on a wave with the maximum value. The trough is the lowest point on a wave. Wavelength is designated by the Greek letter Lambda. Frequency: number of occurrences of a repeating event in the period (=duration of time of one cycle in a repeating event). Phase velocity: rate at which the phase of the wave propagates in space. This is the velocity at which the phase of any component of the wave frequency travels.

KIND OF WAVES: (BY PROPAGATION) Longitudinal waves: when the oscillations are parallel to the direction of energy propagation. Traversal waves: when the oscillation are perpendicular to the direction of energy transfer.

KIND OF WAVES: Mechanical wave: a wave that creates oscillation of matter. Its movement is limited and it transfers energy. Elastic wave: a wave that moves through to an elastic material. (SOUND) (LIGHT )

Sound

Sound is a wave created by vibrating objects and propagated through a medium from one location to another.

The ear is the organ that detects sound. It receives sound and influences balance and body position. The ear is part of the auditory system. The ear has three main parts: the outer ear, middle ear, and inner ear. EAR

PROPERTIES OF THE SOUND

FREQUENCY

LOUDNESS The system used to measure the loudness of sounds is the decibel system, given the unit dB.

TONE Tone depends on the regularity of a sound vibration. A simple tone has only one frequency.. The tone of lowest frequency is called the fundamental; the others, overtones. The speed of sound in air depends on the temperature of the air. The speed of sound is 340m/s at 15°C. SPEED

ECHO The echo depends on the reflection of sound and its return to the ear. The reverberation of a sound happens when the reflected sound- wave returns to the ear in less than 0.1 seconds. REVERBATION

REFLECTION OF SOUND:

The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding. DOPPLER EFFECT

Light

SPECIFIC CONDUCT OF LIGHT WAVES: Reflection. Diffusion. Refraction.

REFLECTION: Reflection is a phenomenon that happens when a ray hit a mirror. REFRACTION: Refraction is a phenomenon that happens when an incident ray hit a plane separating two means. A part of the ray is reflected, while the other portion passes through the second mean and it looks deflected.

LAWS OF REFRACTION: The first law of the refractions says that the incident ray, the refracted ray, and the perpendicular line are in the same plane. The second law says that: (when α is the corner formed by the perpendicular line with the incident ray and β is the corned formed by the perpendicular line with the refracted ray) sen α /sen β is a costant value.

The first law of reflection says that the incident ray, the reflective one, and the perpendicular line to the mirror are on same plane. The incident ray and the reflective ray form with the perpendicular line to the mirror two equal corners. This is the second law of reflection. LAWS OF REFLECTION:

DIFFUSION: Diffusion or scattering is a casual phenomenon and consists in a deflection of light caused by the collision of the particles with other particles.

COLOUR: The visible part of the electromagnetic spectrum is called visible spectrum and it’s composed by electromagnetic waves with wavelenght between 380 – 760 nm. There are three fondamental colours: red, blue and green. Superposing fondamental colours, we gain all the colours of the visible spectrum.

THE CALLING OF ST. MATTHEW This picture by Caravaggio is drawn using dark colors and stripes of lights, that illuminate St. Matthew. The using of lights also gives to observer the direction of picture from right to left. The author decides to use light to underline the call of God to Matthew.

Glossary

Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level

Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level

Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Fate clic per modificare il formato del testo della struttura Secondo livello struttura  Terzo livello struttura Quarto livello struttura  Quinto livello struttura  Sesto livello struttura  Settimo livello struttura  Ottavo livello struttura Nono livello strutturaClick to edit Master text styles Second level Third level Fourth level Fifth level

The End