waves and light - acquire
TRANSCRIPT
Waves and Light Science - 5º
Waves - A disturbance that travels through space and matter transferring energy from one place to another. - Important to remember that they transfer energy, not matter.
Mechanical and Electromagnetic Waves Mechanical waves are waves that require
a medium. This means that they have to have some sort of matter to travel through. These waves travel when molecules in the medium collide with each other passing on
energy. It needs the medium to help it travel. One example of a mechanical wave
is sound.
Electromagnetic waves are waves that can travel through a vacuum (empty space). They don't need a medium or matter. They travel through electrical and magnetic fields
that are generated by charged particles. Examples of electromagnetic waves include light, microwaves, radio waves, and X-rays.
LightLight is a type of energy that makes it possible for us to see the world around us. Light comes from different sources; our main natural light source is the sun. Other sources include fire, stars and man-made light sources such as light-bulbs and torches. Thanks to light, our eyes see different wavelengths of light as different colours. Light also powers the technology around us.
Reflection and Refraction
Reflection occurs when light bounces off objects. How much reflection depends upon how even the surface is. If the surface is rough, the light scatters. If the surface is smooth and flat, the light will bounce off it at equal angles. That is why a flat mirror reflects a good likeness of the object being reflected.
Refraction occurs because light bends.When light moves from one medium (like air) to another medium (like water) it will change directions. This is a "wave-like" behavior and is called refraction. In this way light behaves like other waves such as sound waves. The speed of the light wave also changes when it moves from medium to medium.