https://padlet.com/farramola72/Electromagnetic_Waves Adrian Farramola Period 4 en-us 2017-02-24 14:49:57 UTC 2025-02-21 00:41:30 UTC hello@padlet.com https://padlet-assets.s3.amazonaws.com/icons/Bigthunderstorm.png farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156951332 2017-03-01 09:09:23 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156951332 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156953159 2017-03-01 09:20:14 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156953159 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156954198 Electromagnetic waves are waves which can travel through the vacuum of outer space. Mechanical waves, unlike electromagnetic waves, require the presence of a material medium in order to transport their energy from one location to another. Electromagnetic waves are created by the vibration of an electric charge. This vibration creates a wave which has both an electric and a magnetic component. An electromagnetic wave transports its energy through a vacuum at a speed of 3.00 x 108 m/s (a speed value commonly represented by the symbol c). The propagation of an electromagnetic wave through a material medium occurs at a net speed which is less than 3.00 x 108 m/s. The mechanism of energy transport through a medium involves the absorption and remission of the wave energy by the atoms of the material. When an electromagnetic wave impinges upon the atoms of a material, the energy of that wave is absorbed. The absorption of energy causes the electrons within the atoms to undergo vibrations. After a short period of vibration motion, the vibrating electrons create a new electromagnetic wave with the same frequency as the first electromagnetic wave. While these vibrations occur for only a very short time, they delay the motion of the wave through the medium. Once the energy of the electromagnetic wave is re emitted by an atom, it travels through a small region of space between atoms. Once it reaches the next atom, the electromagnetic wave is absorbed, transformed into electron vibrations and then re emitted as an electromagnetic wave. ]]> 2017-03-01 09:24:48 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156954198 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156954793 2017-03-01 09:27:47 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156954793 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156955290 2017-03-01 09:30:01 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156955290 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156955797
Electromagnetic radiation can be described as a stream of photons, each traveling in a wave-like pattern, carrying energy and moving at the speed of light. In that section, it was pointed out that the only difference between radio waves, visible light and gamma rays is the energy of the photons. Radio waves have photons with the lowest energies. Microwaves have a little more energy than radio waves. Infrared has still more, followed by visible, ultraviolet, X-rays and gamma rays.The amount of energy a photon has can cause it to behave more like a wave, or more like a particle. This is called the "wave-particle duality" of light. The electromagnetic spectrum can be expressed in terms of energy, wavelength or frequency. ]]> 2017-03-01 09:32:01 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156955797 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156957471 2017-03-01 09:39:00 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156957471 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156958266 Radio Waves (communications)

• TV and FM radio (short wavelength)
• Direct line of sight with transmitter (do not diffract)
• Medium wavelength – travel further because they reflect from layers in the atmosphere

Satellite signals (Microwaves)

• Frequency of microwaves pass easily through atmosphere and clouds

Cooking (Microwaves)

• Microwaves are absorbed by water molecules.
• These water molecules become heated > heat food
• Dangers: microwaves are absorbed by living tissue Internal heating will damage or kill cells

Infrared Radiation (remote controls, toasters)

• Any object that radiates heat radiates Infrared Radiation
• Infrared Radiation is absorbed by all materials and causes heating
• It is used for night vision and security cameras as Infrared Radiation is visible in daytime or night-time 
• Police use it to catch criminals, army use it to detect enemy
• Dangers: damage to cells (burns)

Ultraviolet

• Dangers:
  • over-exposure to UVA and B damages surface cells and eyes and can cause cancer.
    • There is a problem with current sunscreens which protect against skin burning from high UVB but give inadequate protection against free radical damage caused by UVA.
    • Dark skins are not necessarily safer from harm.
    • Sun exposure for the skin is best restricted to before 11am and after 3pm in the UK in summer months.
• Benefits:
  • sanitary and therapeutic properties have a marked effect on architecture, engineering and public health and have done so throughout history.
  • UVC is germicidal, destroying bacteria, viruses and moulds in the air, in water and on surfaces.
  • UV synthesises vitamin D in skin, controls the endocrine system and is a painkiller.
  • Used in state of the art air-handling units, personal air purifiers and swimming pool technology.
  • Used to detect forged bank notes: they fluoresce in UV light; real bank notes don’t. Used to identify items outside visible spectrum areas, known as 'black lighting'.

X-rays

• X-rays detect bone breaks
• X-rays pass through flesh but not dense material like bones
• Dangers: X-rays damage cells and cause cancers. Radiographer precautions include wearing lead aprons and standing behind a lead screen to minimise exposure

Gamma Rays

• Gamma Rays cause and treat cancers
• In high doses, gamma can kill normal cells and cause cancers
• Gamma can be used to kill mutated cells though too.

https://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves

]]> 2017-03-01 09:42:18 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156958266 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156958504 2017-03-01 09:43:21 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156958504 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156960195 Radios use radio waves to create sound.]]> 2017-03-01 09:49:53 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156960195 farramola72 https://padlet.com/farramola72/Electromagnetic_Waves/wish/156961003 X-ray machines use x-ray waves to look at Bones and other objects.]]> 2017-03-01 09:53:57 UTC https://padlet.com/farramola72/Electromagnetic_Waves/wish/156961003