Autora: Marta García T.

Light is a kind of electromagnetic energy, formed by very small particles called photons.

The light which allows us to see is called Visible Light.

Autora: Marta García T.

Autora: Marta García T.

Objects can be transparent, translucent or opaque, depending on how light travels through them:

Transparent: they allow light to travel through. Opaque: they absorb or reflect most of the light

they receive, so they don’t allow light to travel through.

Translucent: they absorb some light, and allow some to travel through.

Autora: Marta García T.

Shadows are places where light is “blocked”:

Rays of light

Autora: Marta García T.

1) Light travels in straight lines:

2) Light travels very fast, about 300.000 Km/s in the vacuum.

Laser

Autora: Marta García T.

3) Light Reflection: we see things because they reflect light into our eyes.When a ray of light hits a surface, it bounces off, and begins to travel in a different direction.

Autora: Marta García T.

Autora: Marta García T.

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror

Autora: Marta García T.

Smooth, shiny surfaces have a clear reflection

• Rough, dull surfaces have a diffuse reflection.

Autora: Marta García T.

4) Light Refraction: light is refracted when it passes from one medium to another which has a different density. Light bends at the boundary between the two media.

Ex. Water is denser than air.

Autora: Marta García T.

Lenses are discs made of glass or plastic with one or two curved faces. They refract light. There are two types:

Converging Lenses: they concentrate the rays of light.

Diverging Lenses: they disperse the rays of light.

http://recursostic.educacion.es/newton/web/materiales_didacticos/optica/opt33.htm?2&2Autora: Marta García T.

White light is not a single colour; it is made up of a mixture of the seven colours of the rainbow.

We can demonstrate this by splitting white light with a prism

This is how rainbows are formed: sunlight is “split up” by raindrops.

Autora: Marta García T.

Autora: Marta García T.

The colour of an object depends on the colours of light it reflects.

Ex. A red book only reflects red light:

White

light

Only red light is reflected

Autora: Marta García T.

Autora: Marta García T.

Autora: Marta García T.

Autora: Marta García T.

Autora: Marta García T.

Sound is a form of mechanical energy produced by the vibration of an object.

It travels in waves, and its speed depends on the medium.

In the air: 340 m/s. In water: 1,5 m/s.

http://www.juntadeandalucia.es/averroes/recursos_informaticos/andared01/paisaje_sonoro/sonido.htmhttp://www.juntadeandalucia.es/averroes/recursos_informaticos/andared01/paisaje_sonoro/sonido.htm

Autora: Marta García T.

1) Intensity: sounds can be loud or soft, depending on the amplitude of the wave. It is measured in decibels (dB).

- High amplitude loud sound.- Low amplitude soft sound.

Autora: Marta García T.

2) Pitch: sound can be high or low, depending on the frequency of their waves. It is measured in Hertz (Hz).

- High Frecuency high pitch.- Low Frequency low pitch.

Autora: Marta García T.

3) Tone: it allows you to identify the source of a sound. For example, different instruments have different tones although they play the same musical note.

Autora: Marta García T.