Book 1 ( Waves, Light And The EM Spectrum ) Flashcards
What does the iris do?
The coloured part which controls the size of the pupil.
In bright light the pupil is small.
What does the cornea do?
The cornea is a clear window to the eye.
It helps to focus the light rays
What does the pupil do?
The pupil is the hole which allows some light into the lens and retina.
It protects the retina
What does the lens do?
The lens is able to adjust to create a focused image on the retina
What does the retina do?
The retina contains 130 million light sensitive cells.
What does the optic nerve do?
The optic nerve carries the signals from the light cells to the brain where the picture is seen.
What happens when the ray enters the block at 90 degrees?
It goes straight ahead
It also slows down
What happens when the ray enters the block at any other angle?
It bends
It changes direction and slows down
What happens when the ray comes out of the block at 90 degrees?
It comes straight on
It speeds up
What happens when the ray comes out of the block at any other angle?
It bends back again to the same and,em it came in at
It speeds up
Compare the direction of the ray entering the block with the direction of the ray emerging from the opposite side.
They are parallel but no longer in line with each other.
The ray entering and exiting ray are parallel
When does refraction occur?
When a wave moves from one medium to a different medium and changes speed
When light moves from air to glass it……
Slows down
When light moves from glass to air it………..
Speeds up
Will light bend when it enters a different material at 90 degrees?
No
What is the line at 90 degrees to the surface called?
The normal line
What colour is refracted the most?
Blue
What colour is refracted the least?
Red
What does the brain do so the observer sees an accurate image?
It flips the image
The light from the top of the object focuses on the ………..
Bottom of the retina
Light rays from the bottom of the object ……….
Focus on the top of the retina
What does refracted mean?
When light changes direction when it enters a prism
What is dispersion
When light leaves the prism and spreads out into different colours
In what order do the colours disperse ?
TOP
Ultra red
Red
Orange
Yellow
Green
Blue
Indigo
Violet
Ultra violet
BOTTOM
Why do the colours refract by different amounts?
Because different coloured waves slow down by different amounts
What are the 7 main types of radiation?
Gamma rays
X rays
Ultraviolet
Visible
Infrared
Microwave
Radio
Which has the shortest wavelength?
Gamma ray
Which has the longest wavelength ?
Radio
What is the relationship between wavelength and energy?
The shorter the wavelength, the more energy
What can gamma rays be used for?
Sterilise hospital equipment
Can damage dna
Radiotherapy
What are the properties of x rays?
Medical images -Doesn’t go through bones
Damages dna
Cracks in metal
What are the properties of ultra violet rays
Found in sunlight
Fluorescent lighting
Tanning sun beds
Check banknotes
What are the properties of visible rays?
Only mammals can see them
Photography
Cameras
Tv video
Sight
What are the properties of infrared
Absorbed by skin=heat
Toasters
Grills
Tv remote
Burns
What are the properties of microwave
Can heat tissue
What are the properties of radio
Longest wavelength
Transmit tv programmes
Can be reflected off the inosphere
Which rays can be harmful to life and why?
UV , gamma and x ray
Can damage cells
Infrared can burn you
What is a transverse wave ?
When the vibration of particles within the wave are perpendicular that the energy wave is being transferred
