6.6 Electromagnetic Waves

April 8, 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

http://upload.wikimedia.org/wikipedia/commons/c/cf/EM_Spectrum_Properties_edit.svg

http://upload.wikimedia.org/wikipedia/commons/3/34/Atmospheric_electromagnetic_opacity.svg

Radio waves

Accelerated electrons

Radiowaves

• Communications: TV, mobile phones, local radio, police

Microwaves

Molecular transitions

Microwaves

• Microwaves ovens, communicating with satellites, RADAR

Infrared

Molecular transitions

Infra-red

• Search and rescue teams, detect circulation problems, (cancer, arthritis), astronomy, burglar alarms

Light

Atomic transitions and electron acceleration

Ultraviolet

Atomic transitions

UV

• Produce vitamin D in our skin, suntan, skin cancer

X-rays

Electron transitions and collisions

X-rays

• X-rays (bones, teeth), check welds and joints, food

Gamma rays

Nuclei transitions and annihilation

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