Chapter 9: Light, Colour & Radiant Energy Flashcards
What can refract light into different colours?
Prism
What is the range of colours present in white light called?
The spectrum
What are the 7 main colours (ROY G BIV) called? Give an example
Solar Spectrum
Rainbow
What creates a rainbow?
Light refracted through a rain drop
What happens to light when it strikes an object?
Reflected
Refracted
Absorbed
What colour do we see when all colours are reflected?
What colour do we see when all colours are absorbed?
I. White
II. Black
Why in blue light would a tomato look black?
Because the tomato would absorb all the blue and have no red or green to reflect back.
What are the three additive primary colours?
Red
Blue
Green
What are the secondary colours?
Yellow
Magenta
Cyan
Why are red, blue and green called the additive primary colours?
Why are cyan, magenta and yellow called secondary colours?
Because together they make white light
Because they are made up of the additive primary colours
What are the cells that respond to light called?
Rods and cones
How do rods and cones work?
Rods respond to the presence of light.
There are three different types of cones cells each responding to a different colour (red, blue, green)
What is it called if you have a difficulty detecting some colours?
Colour blindness
What are the secondary colours also called and why?
Subtractive primary colours because they are missing a paret of the white light.
Cyan = Green+Blue (-Red)
Magenta = Red+Blue (-Green)
Yellow = Red+Green (-Blue)
How does light travel?
Wave
What is the high part of the wave called?
What is the low part of the wave called?
Crest
Trough
What is the distance from crest to crest or trough to trough called?
Wave Length
Define Amplitude
The height of the crest or the depth of the trough. Is the maximum distance from sea level
Frequency
The number of complete cycles per second, measured in hertz.
What is the model of light?
It is an idea of how light moves formed by scientist, it is not perfect but it helps our understanding
True or False
Waves spread out more when their wave length is wider?
False
Waves spread out more when their wave length is longer
Conversly, they spread out less when their wave length is shorter
Why is the sky red and orange at sunset?
Because the wavelengths are longer, The shorter wave lengths are typically deflected away
What does LASER stand for
Light Amplification Stimulated Emission Radiation
When light is _______ is has only one wave length
Coherent
Where does the color come from?
White Light
Give five uses for LASERs
i. Read barcodes at the supermarket
ii. Sensing tiny pits on discs
iii. See how fast a car is going
iv. Surgery
v. Cut through metal
Why is it called the electromagnetic field?
Because electric and magnetic fields vibrate in a light wave.
Different colours have different____ and _____.
What colour has the longest wave length? What colour has the shortest?
Frequencies
Wavelengths
Red
Purple
What is infrared light?
Visible light with a slightly longer wavelength
It is used to warm food and baby animals
Infrared sensors are used for burglar alarms and night vision googles.
Radio waves
Longest wave. It is an infrared ray stretched out.
Microwaves
The have the shortest wavelength and hight frequency of any radio wave.
Ultraviolet waves
If you made violet waves a little shorter you would have ultraviolet waves. These waves can be harmful to the skin and cornea. The ozone layer helps protect us from ultraviolet waves. Bees can see these waves
X rays
X rays are even shorter with a shorter wave length that ultraviolet. They penetrate through skin and muscle to the bone. This can be bad because they get absorbed into the bone which isn’t healthy.
Gamma Rays
They have the shortest wave length and can kill cancerous cells. They result from nuclear reactions.
