Electromagnetic Electromagnetic WavesWaves

5.1 The Electromagnetic 5.1 The Electromagnetic SpectrumSpectrum

Learning objectivesLearning objectives

Be able to name the regions of the Be able to name the regions of the EM spectrumEM spectrum

Be able to describe the properties of Be able to describe the properties of a wavea wave

Be able to use the ‘wave equation’Be able to use the ‘wave equation’

What do waves do?What do waves do?

Waves carry energy from one place to another.

There are 2 main types of wave you need to know about:

Transverse Waves e.g. light waves

Longitudinal Waves e.g. sound waves

Types of wavesTypes of waves

What type of energy is the wave transferring?

In which direction is the energy moving?

In which direction is each part of the spring moving?

kinetic

Longitudinal wavesLongitudinal waves

What type of energy is the wave transferring?

In which direction is the energy moving?

In which direction is each part of the rope moving?

kinetic

Transverse wavesTransverse waves

Wave propertiesWave properties

Wave propertiesWave properties

Wavelength (Lambda, Wavelength (Lambda, λλ))

Distance from the Distance from the peak of one wave to peak of one wave to the peak of next wavethe peak of next wave

Energy of wave Energy of wave depends on depends on wavelengthwavelength Radio waves = 1000mRadio waves = 1000m X-rays = X-rays =

0.000000000001m0.000000000001m

Frequency (Hertz, Frequency (Hertz, Hz)Hz)

Number of complete Number of complete waves passing one waves passing one point in a secondpoint in a second

1 Hz = 1 1 Hz = 1 wave/secondwave/second

1 kilohertz = 1000 1 kilohertz = 1000 HzHz

1 megahertz = 1 1 megahertz = 1 million Hz million Hz

Wave speedWave speed

All EM waves = 300 million m/s All EM waves = 300 million m/s (vacuum) (vacuum) Speed of lightSpeed of light

Speed (m/s) = frequency (Hz) x Speed (m/s) = frequency (Hz) x wavelength (m)wavelength (m)

Speed

Wavelength Frequenc

y

Electromagnetic Electromagnetic spectrumspectrum

Electrical and magnetic Electrical and magnetic disturbances that transfer energydisturbances that transfer energy All travel at speed of lightAll travel at speed of light

Energy transferred – wavelengthEnergy transferred – wavelength Put into groups according to Put into groups according to

wavelengthwavelength Different waves lengths = different Different waves lengths = different

effectseffects

Radio

Micro

Infra-Re

dVisible

Light

Ultra-V

iolet

X rays

Gam

ma

Wavelength () increases

High frequency

Short wavelength

High energy

Most penetrating

Low frequency

Long wavelength

Low energy

Least penetrating

The EM spectrumThe EM spectrum

Learning outcomesLearning outcomes

Properties of a wave:Properties of a wave: WavelengthWavelength AmplitudeAmplitude FrequencyFrequency

Using the ‘wave equation’ Using the ‘wave equation’ The EM spectrumThe EM spectrum

Different regions depending on Different regions depending on propertiesproperties

R-M-I-V-U-X-GR-M-I-V-U-X-G