EM Waves

EM Waves

Waves that result from vibrations between an electric and magnetic field

They propagate through space and transfer energy

transverse wave, motion in which all points on a wave oscillate along paths at right angles to the direction of the wave's advance

Requires no medium

Radio waves: Lower than 300 gigahertz

More than 1mm waves

Carry least amount of energy

Used in telecommunication, radio astronomy

Microwaves

300 Gigaheartz to 30000 gigahertz

Wavelength 1mm to 25microm

Microwaves wifi, satellite and spacecraft comms

Infrared

300000 gigahertz to 3000000 gigahertz

Wavelength 25micrometres to 2.5 micrometers

TVs, thermal imaging, infrared astronomy

Visible light

Only part can see with naked eye

Used in lights, seeing things, screens

4-7.5 x 10power14 Hz

Ultraviolet

1015 to 1017 Hz

400nm - 1nm

Sterilising suntanning ultraviolet astronomy

Too much can cause skin cancer, eye damage, fake money identification

X rays

1017 - 1020 Hz

Wavelength: 1nm - 1picometre

Uses: X ray spectroscopy

Gamma rays

1030 Hz most energetic

Wavelength - 1pm shortest

Radiotherapy gamma ray astronomy

So much energy that it rips electrons from atoms which damage tissues and DNA causing cancer.

EM waves can travel through a vacuum

Many objects produce EM waves.

Importance:

Visible naked eye astro constellations and directions

Ultraviolet: determine composition and density of celestial bodies and interstellar medium

X and gamma: Understand energetic events and dark matter.

Satellites allows us to observe and study

Celestial production of EM waves

A charged +- creates electric field

Radio waves: Stars, Planets, galaxies, clouds of dust and molecules of gas + us humans

Microwaves:More energetic than above. Cosmic Microwave background radiation.

Infrared: Anything with thermal energy.

Visible: anything

Ultraviolet: Energetic nebulae or gas clouds, stars or auroras

X rays: Supernovae, hot gases in galaxy clusters, black holes and neutron stars and dark matter

High atomic nuclei release energy in gamma rays.

Gamma rays extremely energetic events like supernovae black holes and celestial collision

Same production.

Special sources: Magnetic field like neutron stars produced

Dangers: Cosmic rays atomic nuclei and high energy photons Focusing optics cannot be used for gamma rays as interaction with matter can cause it to be destroyed or energy can be changed

Cosmic rays can penetrate satellites

Why spend?

To better understand celestial objects with interstellar matter

Find patterns and make useful deductions in similar situations and concepts

Light pollution

You cannot view space under Em waves spectrums of lenses

Several sources can produce EM waves.