The Visible Light Spectrum

What do we Know? What things do you know about “Light” all ready? What can you tell me about the properties of light?

Light is Energy Light is simply a form of energy Light travels in waves Visible light is a range of wave lengths that only makes up a small part of the Electromagnetic Spectrum

What’s in a Wave

Colours of the Rainbow What are the different colours of the rainbow?

Colours of the Rainbow The colours of the rainbow are:RedOrangeYellowGreenBlueIndigoViolet This can also be remembered by the acronym ROY-G-BIV

Rainbows Fun Facts Secondary rainbows display the colours in reverse order from the primary rainbow because the light is reflected twice within the rain drop for a secondary rainbow Notice how the sky appears darker after each rainbow… that is because to the observer, light is reflected at each rainbow and not carried through

Rainbows Fun Facts Only one reflection in a primary water droplet Two reflections in a secondary water droplet

EMS and Waves Now lets open up the Science in Action 8 textbooks to page As we read through the next couple of pages, think about how we see colour and light as well as how much of the total amount of energy passing through our solar system we actually “see”

Light Spectrum Visible light only represents a very small amount of all the possible wave lengths The wave lengths our eyes “see” is a very small portion of the electromagnetic spectrum

Electromagnetic Spectrum

Visible Light Spectrum We see light within the wave length range of about 700 to 400 nanometers Different colours are actually different wave lengths of energy

What do we See? Our eyes have adapted to only be sensitive to light within the visible light spectrum of 700 to 400 nm

What can be Seen? Any other wavelengths of the spectrum we cannot see… however… radios “see” radio waves, infrared cameras “see” heat/infrared waves, and special equipment in hospitals “see” x-rays

Bending Different Colours Which colours refract the most? Which colours refract the least? Answer these questions in your notes now

Separating Light White Light can be separated into the different colours by a prism This is because the different wavelengths are bent in different amounts Red light is bent the least… while violet light is bent the most. The fact that different colour are bent in different amounts is known as “CHROMATIC ABERRATION”

Chromatic Aberration Chromatic aberration is the tendency for red light to bend less than violet light… Therefore the colours will not all converge on the same focal point which blurs an image slightly

Chromatic Aberration You can see how each of the different wave lengths of light (colours of light) are bent differently with a prism… this is due to Chromatic aberration

Rainbows and Stuff Rainbows depend on rain drops and chromatic aberration in order to split light into its different colours A rainbow will always face the observer and will move as the observer moves (no gold for you!!!)

Your Task for Today You are now being given a worksheet that deals with much of the material we have covered in class You must complete this assignment for two classes from now A test is approaching