LIGHT AND OBJECTS
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There are 3 types of objects according to how they react to light: objects can be transparent, translucent and opaque.
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So, as we have seen, light can:
When light is reflected, we call it REFLECTION; while when light passes through objets, we call it REFRACTION.
- Be absorbed by objects and then converted into heat.
- Be reflected by objects.
- Pass through objects.
When light is reflected, we call it REFLECTION; while when light passes through objets, we call it REFRACTION.
REFLECTION
All objects reflect light. Reflected light depends on the type of surface:
All objects reflect light. Reflected light depends on the type of surface:
- Shiny surfaces will reflect a lot of light; dull surfaces will reflect very little light.
- Smooth and flat surfaces will bounce off light at equal angles; rough surfaces will bounce off light at different angles.
REFRACTION
Do you know that the speed of light is not always the same? It can be faster or slower depending on the substance light is passing through. For example: light is faster when it travels through air than when it travels through water.
So, when light passes from one substance to another (for example, from air to water), its speed changes. That speed change causes the light waves to bend (they change their direction). That direction change will depend on the substances light is passing through.
This process is what we call refraction.
Do you know that the speed of light is not always the same? It can be faster or slower depending on the substance light is passing through. For example: light is faster when it travels through air than when it travels through water.
So, when light passes from one substance to another (for example, from air to water), its speed changes. That speed change causes the light waves to bend (they change their direction). That direction change will depend on the substances light is passing through.
This process is what we call refraction.
USES OF REFLECTION AND REFRACTION
- Reflection is used, basically, in mirrors.
- Refraction is used in telescopes, in microscopes, in cameras, in projectors, with fiber optic cables,...; and we use refraction to see. Certain structures in our eyes can change the direction of light. Most refraction in the eye occurs in the cornea.
Let's ease the refraction explanation with a flash animation.
Let's review transparent, translucent and opaque objects with the following flash animation. Click on the picture to see the animation.
Time for videos!
On the first video you will review the reflection of light.
On the first video you will review the reflection of light.
On the second video you will review the refraction of light.
On the third video you could watch a cool experiment using the refraction of light.