Light Notes

Light Notes

by Ms. Bryant

​Measuring Light

• We measure light by 3 different properties:

  • Brightness

  • Color

  • Visibility​

​Color

• ​Light, or "white light", is made up of ALL colors of light mixed together.

• ​If white light passes through a prism, it can be separated into all of the colors.

• ​Those colors are red, orange, yellow, green, blue, and violet -- the colors of the rainbow!

​Brightness

• ​The intensity of light is how we measure how much light we can see.

• ​The closer the source of light is, the brighter it is.

  • ​Think of a flashlight. If you hold it up close to your face, it hurts your eyes to look at.

• ​The farther away the source of light is, the less bright it is.

  • ​If someone with a flashlight is far away from you, you can still see the light, but looking at the flashlight won't hurt your eyes as much.

​Visibility - an object's ability to be seen

• ​In order for us to see an object, it has to either give off its own light or reflect light.

  • ​What are some objects that gives off their own light?

• ​This means everything that does not make its own light reflects light to be seen.

  • ​That even means us! Think about it, if we are in a dark room, you can't see another person or objects. This is because there is no light for us to reflect.

​What happens when light hits objects?

• ​Light can do 3 things when it hits an object. It can be:

  • ​Reflected

  • ​Refracted

  • ​Absorbed

​Reflection

• ​When light is reflected, it bounces back from a surface.

• ​This is how we see objects that don't make their own light - it bounces off the surface/object and reflects light into our eyes.

• ​When light hits a shiny or smooth surface, like a mirror or still water, it is reflected and can show us a reflection very similar to the object seen.

• ​The color of the light that is reflected is the color we see. For example, something red only reflects red light.

​Refraction

• ​When light is refracted it passes from one type of material and changes direction.

• ​A great example of this is a magnifying glass. When light passes through, it changes directions, which lets us see a much bigger version of what we are looking at.

​Absorption

• ​When light is absorbed it does not reflect or pass through the object. It remains in the material as a form of energy,

• ​The colors of objects are determined by the light that is not absorbed and then reflected for us to see. All other colors of light striking the object are absorbed.

  • ​For example - if you are wearing a blue shirt - white light strikes your shirt. All colors EXCEPT for blue are absorbed. Blue is reflected to our eyes.

​Now, let's check your understandingof Light!

Multiple Choice

What was this lesson about?

• Light

• Fractions

• Space

• The Solar System

Open Ended

What are the 3 properties that we look at to measure light?

Poll

In our "Color" slide, we talked about what happens to light when it passes through a prism. What happens to that white light?

• It separates into all fo the colors.

• Nothing happens to the white light.

Open Ended

What happens when light hits objects? (Think about the 3 things that light can do.)

​Check your answers!

1. ​What was this lesson about? SPACE

2. ​What are the 3 properties that we use to measure light? BRIGHTNESS, COLOR, VISIBILITY

3. ​In our "Color" slide, we talked about what happens to light when it passes through a prism. What happens to that white light? IT SEPARATES INTO ALL OF THE OTHER COLORS.

4. ​What happens when light hits objects? IT CAN BE REFLECTED, REFRACTED, or ABSORBED.