14 Electromagnetic Waves.pdf

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What we will learn …



Electromagnetic (EM) Waves

•

What are EM Waves

•

Properties of EM Waves



Uses of Electromagnetic (EM) Waves

•

Applications of EM Waves

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For this section …



Describe the

main components

of the

electromagnetic

spectrum

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Welcome to the world of …

Technology



Using the mobile phone



Using wireless computers



Listening to radio



Watching TV



Cooking using microwave oven

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What are

Electromagnetic Waves ?



An electromagnetic wave is produced by the

simultaneous

vibration

of

electric

and

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What are



Electromagnetic waves, which include light,

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What are



Main components of the EM spectrum:

•

Radio waves

•

Microwaves

•

Infrared

•

Visible Light

•

Ultraviolet

•

X-rays

•

Gamma rays

EM Spectrum

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Longest Wavelength

Shortest Wavelength

Lowest Frequency

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What are



The electromagnetic spectrum is

continuous

so

all possible frequencies that exist in this range

can be found.



There is

no distinct boundary

between one

type of electromagnetic waves and the next.



Gamma rays

(



-rays) have the shortest

wavelength

and the

highest frequency.



Radio waves

have the longest wavelength

and

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Properties

of

Electromagnetic Waves

Property #1



The wave direction is perpendicular to the

direction of vibrations

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Properties

of

Property #2



They transfer

energy

from one place to

another

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Properties

of

Property #3



They can travel through a

vacuum

.



They do not require any medium to travel from

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Properties

of

Property #4



They travel at

3 x 10

8

ms

-1

(speed of

light

) in

vacuum

.



They will slow down when travelling

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Properties

of

Property #5

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Properties

of

Property #6



They all show wave properties like

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Properties

of

Property #7

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Properties

of

Property #8



Their

frequency

do not change when they

travel from one

medium

to another.



Only their

speed

and

wavelength

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For this section …



State the

applications

of electromagnetic

waves

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Applications

of

Gamma Rays  Radiation Therapy (Cancer Treatment)

X-Rays  Medical imaging (checking for bone fractures)

Ultraviolet Rays  Sunbeds

 Sterilisation of medical equipment

Visible Light  Optical Fibres

Infrared  Remote Controllers  Ear Thermometers

Microwaves  Microwave ovens

 _{Satellites Communication}

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Applications

of

Gamma Rays  Radiation Therapy (Cancer Treatment)

•

It can be used to treat cancer.

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Applications

of

X-Rays  Medical imaging

•

Used to produce the X-ray images used to diagnose the fracture of a broken arm or tooth decay

•

used in X-ray scanners in airports

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Applications

of

Ultraviolet Rays

 Sunbeds

 Sterilisation of medical equipment

•

Ultraviolet (UV) radiation is divided into three bands in order of increasing energy: UVA, UVB and UVC

•

Ultraviolet lamps that emits UVA are used in sunbeds for artificial tanning

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Applications

of

Visible Light  Optical Fibres

•

Light is used in optical fibres for medical purposes and telecommunications

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Applications

of

Infrared  Remote Controllers  Ear Thermometers

•

Infrared remote controllers are used to control a variety of

electrical devices such as the TV

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Applications

of

Microwaves  Ovens  Satellites

•

In the microwave oven, the microwaves cause the water molecules in food to vibrate at millions of times a second

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Applications

of

Microwaves  Ovens  Satellites

•

Satellite television use microwaves to receive television programmes via satellites in space

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Applications

of

Electromagnetic Waves

Radio Waves  Radio

 Telecommunications

•

They are not only used in radio broadcasting but in telegraphy, telephone transmission, television, radar, navigation system and telecommunications

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Effects

of Electromagnetic

Waves

Infrared

Heating

Effects

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Effects

of Electromagnetic

Waves

Barbecue Pit

At barbecue parties, our skin absorbs infrared waves, making us feel warm.

Thermal Blankets

Thermal blankets trap infrared waves from the Sun, which warms our body in cold weather.

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Effects

of Electromagnetic

Waves

Ionisation

 High energy electromagnetic waves such as

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Effects

of Electromagnetic

Waves

Ionisation

 Ionisation radiation can damage biological molecules and lead to abnormal pattern of cell division.

 At the molecular level, exposure of ionisation radiation on human tissues may damage proteins and DNA

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Effects

of Electromagnetic

Waves

Ionisation

Ionisation radiation can cause the following damage to the human body:

 At the molecular level, exposure of ionisation radiation on human tissues may damage proteins and DNA

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Effects

of Electromagnetic

Waves

Ionisation

Ionisation radiation can cause the following damage to the human body:

 A pregnant woman exposing her developing foetus to ionising X-ray imaging may run the risk of giving birth to a deformed baby

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Effects

of Electromagnetic

Waves

Ionisation

 Ionisation radiation can cause the following damage to the human body:

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