#1 Flashcards
Electromagnetic Waves def
Transvere waves consisting of a combination of oscillating electric & magnetic fields
What are the origins of a force
Fields
Speed of light in a vacuum
3 X 10^8 m/S
Or 186,000 miles/S
Dual or nature def
Light can either be a wave or a particle (photon)
EM Waves are different from mechanical waves in 2 ways?
1) EM is a comb of 2 waves - 1 cannot exist without the other
2) EM do not need a medium
All parts of a transverse apply to
EM waves
EM Spectrum
1) Radio, Micro, infrared, visible, ultraviolet, xray, 7) gamma rays
Low energy photon - High energy photon
Radio def
< 100hz - 1x10^9 hz
Usually given in KHz or MHz
Used for communication
High frequency needed for space communication
Commercial bond=
88-108 MHz
Microwaves def
1x10^9 - 1x10^12
Microwaves are used for what
1) Radar - microwaves
2) communication - Bluetooth, wifi
3) cooking - 2450 mHz, wavelength of 0.122m
How do microwaves cook food
By raising energy of molecules directly
No convention or conduction
Water molecules oscillate ?
Back and forth & increasing KE, increasing temp
Infrared(IR)
1x10^12 - 4x10^14
Everything emits
IR
As atoms vibrate they
Release IR
As cooler atoms absorb IR, they
Vibrate more
What are infrared used for
Wireless control(TV, stereo, Xbox) Emit coded IR
Visible light def
4x10^14-7.5x10^14
ROYGBV
44% of suns radiation is visible light
Ultraviolet def
7.5x10^14-1x10^18
7% of sun is
UV
Doesn’t heat as much as IR, but causes chemical reaction that tans skin
Can cause change to DNA
Fluorescence def
When certain substances are hit with UV, they emit visible light
Visible light def
Coat light with substance, excited atoms in tube produce UV, UV hits coating and it glows
X-rays
1x10^18 - 1x10^20
X-rays - wavelength is the same size as
Spaces between atoms in solids
- show how atoms are arranged
Body materials absorb X-rays
Differently
Materials with Ca absorb X-rays
Easily
Materials with C, H & O
Don’t absorb X-rays
Materials with very large atoms(lead=82)
Absorb X-rays very well
Gamma rays
1x10^20-1x10^23
Radioactive decay produces
Gamma rays
Nuclear fission
Pull apart
Nuclear fusion
Smash together
White light is
A combo of equal amounts of all the colors
Black color is the
Absence of light; lack of reflection
Reflection did
All objects reflect light(excpect pure black)
Two types of reflection
1) speculator reflection
2) diffuse reflection
Speculate reflection def
Reflection off a smooth surface
Low of reflection =
Qi=Qr
Diffuse reflection def
Reflection off of a rough surface
Still follows law of reflection
