ANDREA BOYANO MARIA TORANZO

LIGHT AND SOUND

1.WHAT IS THE LIGTH? Light is a form of energy.

We can see objects because they reflect light.

They can be natural or artificial.

2.WHAT IS THE LIGHT? The Sun is a source of natural light.

A light bulb is a source of artificial light.

HOW DOES LIGHT TRAVEL? Light travels in straight lines and in all

directions from the source of light.

Light travels very quickly, at 300,000 kilometres per seconds.

THE EFFECT OF LIGHT ON MATERIALS. Light passes through transparent

materials.

Only part of the light passes through translucent materials. Light rays separate into different directions.

Light does not pass through opaque materials.

REFLECTION Reflection lets us see objects that do not

emit light. When light reaches an opaque object, it hits the object and light changes its direction. It reflects the light.

When we look in a mirror, we see our reflection in it because light rays do not separate.

1.REFRACTION When a ray of light goes from air to

water, its speed changes. As a result, the ray changes its path. This is called refraction.

o When white light passes through a drop of rain, the ray of light refrects. Each ray of colours separates, forming a rainbow.

o Light also refracts when its passes through a lens. There are two tipes of lenses, coverging and diverging.

2.REFRACTION

1.THE USES OF LENSES.

Glasses and contact lenses.

Projectors:

Telescopes and binoculars.

Magnifying glasses and microscopes.

2.THE USES OF LENSES.

WHAT IS SOUND?

Sound is a form of energy produced by vibrations.Our vocal cords vibrate and create our voices.

THE CHARACTERISTICS OF SOUND Intensity. Sounds can be soft or loud.

Pitch can be high or low.

Timbre is the quality of a sound.

HOW DOES SOUND TRAVEL? Sound travels in all directions and In

straight line.

Sound is slower than light.It travels at 340 metres por second.

ECHO AND REVERBERATION. When the sound waves reach an

obstacle,they reflect in two different ways:

Echo happens when the obstancle is more than 17 metres away.

Reverberation happens when the obstacle is a shoter distance away.The reflected sound mixes with the emitted sound.