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The EM Spectrum22 April 2023

ObjectivesBe able to describe the order of the em-

spectrum and know how fast light travels.

HSW: AF5: Process data using multi-step calculations to identify complex relationships between variables.Used before in: Will use again in:

PLTS: Independent enquirers: support conclusions, using reasoned arguments and evidence.

Used before in: Will use again in:

KeywordsWavelength, lamda, amplitude, frequency, Hertz, kilohertz,

megahertz, speed, metres, kilometres.

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Outcomes

All students should be able to: Describe that there are different types of

visible and invisible light each with different properties.

Most students should be able to: State the speed of light.Some students should be able to:Explain that the em-spectrum can be

described in different sections because of different wavelengths and frequencies and that this effects how much energy the light has.

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Electromagnetic Radiation

E-M radiation is basically a movement of energy in the form of a wave. Some examples:

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Practical Time

• Dispersion practical.• Can you split light up?• What do you see?

• Now watch the demo

• Draw what you see (how can you remember what you see?)

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The Electromagnetic Spectrum

• Demonstration • Your teacher will show you the EM-

Spectrum and describe the sections.

• How do we know they are all there?• Why aren’t there any more than this?

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The Electromagnetic Spectrum

Gamma rays

X-rays Ultra violet Visible light

Infra red Microwaves

Radio/TV

Each type of radiation shown in the electromagnetic spectrum has a different wavelength and a different frequency:

Each of these types travels at the same speed through a _______ (300,000,000m/s), and different wavelengths are absorbed by different surfaces (e.g. infra red is absorbed very well by ___________ surfaces). This absorption may heat the material up (like infra red and _______) or cause an alternating current (like in a __ _______).

Words – black, microwaves, long, short, TV aerial, vacuum

High frequency, _____ wavelength

Low frequency, _____ (high) wavelength

γ

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Order of EM Spectrum

• R• M• I• V• U• X• G

• Randy• Monkeys• In• Velvet• Underpants• Xterminate• Gibbons

• Radio• Microwaves• Infra-red• Visible• Ultraviolet• X-Ray• Gamma

Your turn – come up with your own

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

BAKER’S “PLAY YOUR EM CARDS RIGHT”

TRY AGAIN

Is the Wavelength Higher or Lower?

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

higher

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

higher

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

lower

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

higher

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

lower

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X-rays Ultra violet Visible light

Gamma rays

Microwaves

Infra red Radio/TV

γ

TRY AGAIN

higher

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The Electromagnetic Spectrum

Gamma rays

X-rays Ultra violet Visible light

Infra red Microwaves

Radio/TV

γ

The correct order – how can we remember it?

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