Electromagnetic Waves

Electromagnetic Waves

a wave capable of transmitting its energy through a vacuum

Electromagnetic Spectrum

Radio waves

Microwaves

Infrared (IR)

Visible Light

* RED
* ORANGE
* YELLOW
* GREEN
* BLUE
* VIOLET

Ultraviolet (UV)

X-Rays

Gamma Rays

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Wavelength Decreases frequency increases as you go down

How are electromagnetic waves formed?

By a varying magnetic field that induces a varying electrical field. The waves consist of these induced oscillating electric and magnetic fields that are perpendicular to each other.

Properties of Electromagnetic Waves (EMW)

EMW behave like waves and particles

* all EMW are transverse
* Wave like properties
* reflects
* refracts
* diffracts
* disperses
* interferes
* Particle like properties
* produce pressure on surface
* having momentum (Compton effect)
* releasing electrons from metal surface (photoelectric effect)
* EM radiation consists of energized particles creating waves of energy with no mass
* All EMW travels at the same speed (c=3x10^8m/s)

Radio waves

* Longest wavelength, allowing it to travel far distances
* Lowest frequency
* easily transmitted through air
* harmless to human cells when absorbed
* transmit coded information through long distances

Microwaves

* Microwaves heat food using a Megatron that generates microwaves → reach the water molecules in the food causing them to vibrate → increase in friction leading to increase in temp
* Used in: communication, Wi-fi and satellites, high frequencies and easy transmission through atmosphere, MW can carry information + transmit this information from earth to satellites

Infrared (IR)

* longer wavelengths than visible light
* thermal radiation in the form of IR EMW is emitted by all matter with temp above 0
* can be transmitted through atmosphere
* used: for communication + Fibre optics, sensors, IR thermal imaging for medical diagnoses, thermal cameras and heating

Visible Light

* not absorbed by earths atmosphere
* scattered due to gas and dust → different colors in the sky
* Fibre optics communication, photography, TV and smartphones

Ultraviolet (UV)

* when illuminating object with phosphorus, visible light emitted
* used: to cure harden/ cure some materials, detect structural defects, sun tanning, fluorescent light, sterilization
* Can cause sunburn, harm living cells and cause premature ageing of skin/ skin cancer

X-Ray

* highly energetic waves, penetrate matter
* ionizing radiation (Radiation that can displace electrons from shells of atoms to make ions) can cause DNA mutations → cancer
* Used: medical and industrial imaging due to penetrative characteristics

Gamma Rays

* highest energy, made in radioactive decay
* shortest wavelength and highest frequency
* can penetrate matter, ionizing radiation, can damage living cells
* mostly absorbed by earths atmosphere
* uses:
* medical sterilization and treatments, radiotherapy
* nuclear studies/ nuclear reactors
* security (smoke detection, food sterilization)
* astronomy

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