e.m.waves

Stopwatch Graph Home

The EM SpectrumLesson 01: DispersionLesson 02/03: The EM SpectrumLesson 04: Pupil ResearchLesson 05: Pupil Presentations

Dispersion 01/05/23

Aim:• To be able to explain the cause of dispersion• To explain the nature of the electromagnetic

spectrum

Starter:

DispersionThe white light ray is split into a spectrum of colours. This is known as DISPERSION.

The different colours of light have different wavelengths. Different wavelengths are refracted different amounts.

Red light is refracted least.

Violet light is refracted the most.

Which colour is refracted the most?How do you remember the order of the colours?Richard Of York Gave Battle In Vain

Colour, Wavelength and Amplitude

Dispersion Summary

Red/violetRefracted more/less

by glassLonger/shorter

wavelength

Red/violetRefracted more/less

by glassLonger/shorter

wavelength

Definitions All Electromagnetic waves are energy waves They can travel through a vacuum They all travel at the speed of light (300 000 000

m/s) We group them by their properties and hence

uses, inside each group is a range of frequencies.

Electromagnetic SpectrumRadio

Infra-Red

Ultra-Violet

X rays

a Wavelength () increases

High frequencyShort wavelengthHigh energyMost penetrating

Low frequencyLong wavelengthLow energyLeast penetrating

The EM Spectrum recapAim:•To explain the dangers and uses of the EM Spectrum

Light, a type of radiation, is part of the electromagnetic spectrum.The electromagnetic spectrum is made up of different types of radiation.The different types of radiation have different properties and behaviour.All electromagnetic waves can travel through space.All electromagnetic waves travel at the same speed in a vacuum [300,000,000 m/s].

TRUE/FALSE

Starter:

The Electromagnetic Spectrum 01/05/23

Aim:• To explain the uses and dangers of the EM Spectrum

Electromagnetic SpectrumRadio

Infra-Red

Ultra-Violet

X rays

a Wavelength () increases

RememberMyInstructionsVisibleUnderX – RayGlasses

High frequencyShort wavelengthHigh energyMost penetrating

Low frequencyLong wavelengthLow energyLeast penetrating

Uses and dangers of EM radiationCopy the Top of the following table into your books(we will fill it in as we go)

Radiation Uses DangersGammaX-rays

UltravioletLight

Infra redMicrowaves

Radio waves

HighLevelnuclearwasteMicrobes can be

killed using gammaradiation

Increasingdose tumour

view throughthe head

healthybraintissue

Gamma rays can be used to treat brain tumours

EM Radiation:

Dangers:

sterilising surgical equipment and food, killing cancer cells.

High doses can kill cells. Lower does can cause cancer (brain, liver, bone, leukemia…)Sterility

X-raytube

Jumbo jet wings are regularly checked in this way to see if any micro-cracks have developed. These small cracks are too small to see any other way and could have fatal consequences.

X-raytube

Detection of broken bones in the body

Customs X-Rays are used to scan luggage in customs

Damage to organs.X-rays can penetrateto the vital organs inside the body.

EM Radiation:

Dangers:

Shadow pictures of luggage and inside the human body.

High doses can kill cells. Lower doses can cause cancerSterility

X rays

Stopwatch Graph HomeMovie Friends

Outer dead skin cells Outer dead skin cells

Living skin cells Living skin cells

The effect of UV on cells

EM Radiation:

Dangers:

Sun beds, fluorescent lamps and security marking.

Sun Burn.Skin cancerBlindness

Ultraviolet

Optical Fibres

Optical fibres, that are used in communication, use total internal reflection.

What are the applications of total internal reflection?

EM Radiation:

Dangers:

Photography and endoscopes

Blindness

How do infrared waves cook food?

Night vision

All objects above absolute zero emit infrared radiation. The hotter an object is, the more heat radiation it emits. Some animals and cameras can detect infrared radiation and are able to build up a heat picture.

Which are the hottest/coolest parts of

the image shown?

light is hot

dark is cold

Fireman

Walking in the Woodland

Uses of infrared – activity

EM Radiation:

Dangers:

Remote controls, radiant heaters, grills, optical fibre communication, night vision, Mobile Phones

Skin burns

Infrared

Microwave ovenThe microwaves have the exact wavelength(frequency) to be absorbed by the water moleculesThe molecules move faster

The water temperatureincreases

EM Radiation:

Dangers:

Satellite communication, mobile phones, cooking, RADAR.

Internal tissue heating.

Microwaves

EM Radiation:

Dangers: None is found

Communication and astronomy.

Radio waves

The electromagnetic spectrum

Energy of electromagnetic waves

Effect of electromagnetic waves

EM Questions1) Match up the following parts of the electromagnetic spectrum with their uses :

Gamma rays Allow us to see

Radio waves Remote Controls

Ultra Violet ‘See’ broken bones

Visible Communications

Microwaves RADAR

X rays Sterilise equipment

Infra Red Causes sun-tans

EM Questions

2) Which radiations are missing from below?

Gamma A Ultraviolet Light Infrared B Radio waves

A. ___________

B. ___________

X raysMicrowaves

Electromagnetic Spectrum

e.m.waves

Education

systemic design principles & methods isss 2014

disruptive innovations in education

from sea to sertão

world cup lesson ideas, resources, & apps

influence through storytelling

study of animal tissue

ways to get technology for your classes

getting students to vlog their learning with vine &...

teaching with vine

nigeria and the royal niger company- full story

fresh, fresher, freshest: building vocabulary through rhythm...

july 2014 complete current affairs - banking and finance +...

digital dialogues: speaking activities, web tools & apps...

digital adventures with avatars! tips & resources for...

meaningful elearning with digital badges & missions

how to use guest posts to grow your following on instagram

principles of presenting yourself- the path to...

future trends in higher education marketing

learning design and personal learning networks

digital poets! web tools, apps, & lesson ideas