Lesson 2

EM Wave

Electromagnetic waves

Waves that result from the vibrations between an electric and magnetic field (hence the name)

They propagate through space and transfer energy

Transverse waves: the oscillate perpendicular to the direction of propagation

Electric field is perpendicular to magnetic field

Many objects in space produce Em waves of some wort

They can transfer energy through a vacuum

As such, astronomers are able to observe close to every thing in the universe by utilising different parts of the spectrum

Radio waves

Frequency: lower than 300 GHz (lowest)

Wavelength: more than 1mm (longest)

Carries the least amount of energy throughout the spectrum

Used in telecommunication, radio astronomy etc.

Microwaves

Frequency 300GHz to 30000GHz

Wavelength: 1mm to 25μm

Used in: microwave, satellite and communication

Infrared radiation

Frequency: 300000GHz to 300000GHz

WavelengthL 25μ to 2.5μm

Used in: TV remotes, heaters , thermal imaging, infrared astronomy etc.

Visible length

Frequency: 4-7.5x10^14Hz

Wavelength: 750NM - 400NM

Ultraviolet light

Frequency: 10^15 - 10^17 Hz

Wavelength: 400nm - 1 m

Used in: sterilisation, creating fluorescent effects, suntanning

Risk: Cancer, Skin damage, Eye damage and Immune system suppression

X-rays

Frequency 10^17 - 10^20 Hz

Wavelength: 1nm - 1pm

Uses: X-ray spectroscopy, X-ray astronomy

Risk: Cancer

Gamma rays

Frequency: >10^20 Hz, most energetic

WavelengthL <1pm, weakest wavelength

Uses: Radiotherapy (killing cancer), Sterilisation and Disinfection

Risk: They pass through the human body completely while repping electrons from atoms which damage tissue DNA, cause cancer, radiation sickness and Walking Ghost phase since they has so much energy

Importance of Radio: satellite communication and radio wave emitters

Importance of microwaves: also satellite communication, microwave emitters and the cosmic microwave background

Importance of Visible waves: Naked eye astronomy, constellations and directions, stars, Doppler redshift

Importance of Ultraviolet waves: Used to determine composition, density, and temperature of celestial bodies and interstellar medium

Importance of X and Gamma rays: help us study and understand energetic events and objects and even dark matter.

Importance of Infrared waves: observe the universe by its temperature (some parts of which may be other wise invisible) emitted by anything with heat energy

SOURCES:

EM Waves

A charged particle creates an electric field

a moving charged particle creates a magnetic field

an accelerating charged particle produces EM waves

Radio Waves

Stars, Planets, Galaxies, clouds of dust and humans

Microwaves

Similar to radio waves but more energetic, and plus cosmic microwave background

Infrared radiation

anything with thermal energy and/or strong magnetic fields

Visible light

Anything you can see

Ultraviolet light

Energetic nebulae or gas clouds, stars, galaxies, even aurorae

X-rays

supernova, hot gases in galaxy clusters, black holes and neutron stars, and even dark matter

Gamma-rays

Extremely energetic events suck as supernovae, blackholes and celestial collision, so that we may learn how these events shape the universe

Special sources of EM waves

Neutron stars

Relfection:

The seats really have no back support

I tried taking down all the slides but my fingers got tired

My team put in effort for making slides but we didnt present

my back really aches

Of everything the presenter says i only hear about 85%?

Maybe less. Can you increase the volume?

Google Landscape is pretty fun to mess around with

Will we be getting the Universe Sandbox anytime soon?

Im tired, my eyes feel like raisins