6.6 Electromagnetic WavesApril 10, 2023
Think about:•How well behaved you are•How good you are at science•How much you like chocolate hob nobs
Aims
• Describe visible light as part of the electromagnetic spectrum
• State other types of radiation
Electromagnetic waves
Travel through empty space
Travel at 300 000 km/s
Transverse waves
They transfer energy
Light vs Sound
Example of wave LIGHT SOUNDType of wave
Speed in air / km/s
Material of medium
Light vs Sound
Example of wave LIGHT SOUNDType of wave Transverse Longitudinal
Speed in air / km/s
300 000 340
Material of medium
No material required
Solid, liquid, gas
Example of wave LIGHT SOUNDType of wave
Speed in air / km/s
Material of medium
Example of wave LIGHT SOUNDType of wave
Speed in air / km/s
Material of medium
Electromagnetic radiation actually comes in packets
or lumps. I call these packets ‘quanta’. A quanta of light is called a photon.
Nobel prize please…
The higher the frequency, the more energy the photon has
Intensity
Energy of each photonNumber of photons arriving each second
The electromagnetic spectrum
Radio waves
Radiowaves
• Communications: TV, mobile phones, local radio, police
Microwaves
Microwaves
• Microwaves ovens, communicating with satellites, RADAR
Infrared
Infra-red
• Search and rescue teams, detect circulation problems, (cancer, arthritis), astronomy, burglar alarms
Light
Ultraviolet
UV
• Produce vitamin D in our skin, suntan, skin cancer
X-rays
X-rays
• X-rays (bones, teeth), check welds and joints, food
Gamma rays
Gamma rays
• Make Hulks, sterilise food and utensils, tracers, radiotherapy
RECALL THE DETRIMENTAL EFFECTS OF EXCESSIVE EXPOSURE OF THE HUMAN BODY TO ELECTROMAGNETIC WAVES
3.13
Make an EM spectrum booklet
Guest starring Mr. Simon Porter
The EM spectrum
• You now have seven sections to fill in with information regarding the seven types of electromagnetic radiation
• Include uses, dangers, detectors, examples and origins if you can
• The better you make it the better it will help your revision