Physics Revision Lesson 2

8/13/2019 Physics Revision Lesson 2

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Understanding Sound

Waves,Ultrasound and the

Electromagnetic Spectrum

Physics Revision Lesson 2


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In this lesson you will revisit:

Sound waves !particularly ultrasound"#

Seismic Waves

$he Electromagnetic Spectrum


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Sound Waves

%an &e re'lected and re'racted#

Echoes are due to re'lected sound#

$he amplitude o' a sound wave is a measure o'how much energy is &eing carried# (igger

amplitude means louder sound#

)re*uency o' a sound determines its pitch#)re*uency is measured in hert+# igh 're*uency

leads to high pitch and vice versa#


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Wave $races

A high pitch sound. A low pitch sound.

A quiet sound. A louder sound.


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Ultrasound $his is sound with a higher 're*uency than

we can hear, i#e# a&ove 2---- +#

Uses include: industrial cleaning, &rea.ing

down .idney stones, industrial *uality

control, scanning o' un&orn &a&ies and

S/01R#


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A louder sound.

X rays are more energetic and penetrating and are a lot more

dangerous, they could cause damage to the growing baby.

Why do doctors use ultrasound to scan the foetus and not

X rays which give a clearer picture?

Ultrasound has many uses, especially in medicine where it

is used to scan the foetus.

1 wee!s " wee!s

Using #ound Waves $ Ultrasound


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#eismic Waves %&arthqua!e Waves'

(uring an earthqua!e the two types of wave that are

released from the epicentre are primary waves %p)waves'and secondary waves %s)waves'.

*rimary or p)waves are the fastest. +hey are

longitudinal in nature and when they hit the surface theyma!e obects and buildings vibrate vertically. +hey can

travel through solids and liquids.

#econdary or s)waves are the slowest. +hey aretransverse in nature and when they hit the surface they

ma!e obects and buildings vibrate hori-ontally. +hey can

only travel through solids.


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ou will need to .now how seismic waves can tell

us a&out the Earth3s structure#

uter core

/rust

0antle

nner core

&arth2s #tructure


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&lectromagnetic #pectrum

Although all e)m waves travel at the same speed, their

wavelength 34 and frequency 354 can be different.

+he properties, dangers and uses of e)m waves depends

on the wavelength 34.

Waves that coo! food.

Waves that cause

sun)tans.


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6adio

0icro

1nfra)

6ed

7ight

Ultra)

8iolet

Xrays

9amm

a

Wavelength %' increases

/an you thin! of a phrase that would help you remember this order? Gate X Usually Lets In Most Radiation

:igh frequency

#hort wavelength

:igh energy

0ost penetrating

:igh frequency

#hort wavelength

:igh energy

0ost penetrating

7ow frequency

7ong wavelength

7ow energy

7east penetrating

7ow frequency

7ong wavelength

7ow energy

7east penetrating


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Uses and dangers of &0 radiation

6esearch the uses and dangers of the various radiations$

6adiation Uses (angers

9amma

X)rays

Ultraviolet

7ight

nfra red

0icrowaves

6adio waves


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&0 6adiation$

Uses$

(angers$

;ills harmful bacteria in

food, sterilising surgical

equipment, !illing cancercells.

:igh doses can !ill cells.7ower doses can cause

cells to become cancerous.

9amma


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&0 6adiation$

Uses$

(angers$

#hadow pictures of

luggage and inside the

human body.

:igh doses can !ill cells.7ower doses can cause


X rays

:ospital wor!ers limit

e


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X rays

X rays can

penetrate soft tissue

but not b=====. Xrays are a=======

more by some

materials than

others. *========f==== is used to

detect X rays.

onebsorbed

hotographicilm

:ow are X rays slides formed?


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&0 6adiation$

Uses$

(angers$

#un beds, fluorescent

lamps and securitymar!ing.

:igh doses can !ill cells.

7ower doses can cause


Ultraviolet Which type of radiation isthe most dangerous?

+he higher the frequency

of the radiation, the moredangerous it is. #o

gamma is more

dangerous than X rays or

ultraviolet.


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&ffects of &0 radiation on living cells

nfra red radiation is used in toasters, grills and radiant

heaters.

What effect do you thin! it has on your s!in?

Ultraviolet radiation can pass through s!in to deeper

tissues.

What effect do you thin! the colour of the s!in has on

the amount of radiation that passes through it?

+he dar!er the s!in, the more ultraviolet radiation is

absorbed, the less can reach into deeper soft tissues.


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&0 6adiation$

Uses$

(angers$

#eeing and endoscopes

>lindness

7ight


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&0 6adiation$

Uses$

(angers$

6emote controls %+88/6',radiant heaters, grills, optical

fibre communication, night

vision.

#!in burns

nfrared

Whi h th


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@ight vision

All obects aboveabsolute -ero emit

infrared radiation. +he

hotter an obect is, the

more heat radiation itemits. #ome animals

and cameras can detect

infrared radiation and

are able to build up a

heat picture.

Which are the

hottestcoolest parts of

the image shown?

light is hot

dar! is cold


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&0 6adiation$

Uses$

(angers$

#atellite communication,

mobile phone networ!s,coo!ing, 6A(A6.

nternal tissue heating.

0icrowaves


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0icrowaves

0icrowaves can be used in

c===== because many foods

contain w==== molecules.

0icrowaves of the rightw======== are able to ma!e

the water molecules r=======.

+his causes the food to get

h====.

:ow do microwaves coo! foods?

oo!ingater

avelength

esonate

otter

6 di


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&0 6adiation$

Uses$

(angers$

/ommunication andastronomy.

6adio waves

6adio waves


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6adio waves

:ow do radio signals from the U; reach around the globe?

+he longer

wavelength radio

waves from atransmitter reflect

off the &arth2s

outer atmosphere

%ionosphere'.

9


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9etting hotter

f electromagnetic radiation is incident upon a

material what effects could it have?

An alternating current could be induced in the material,

with the same frequency as the incident radiation.

+he temperature of the material could increase.

245 %6-5 %7-5 %8-5 %


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What is the upper range of human hearing?

A. " :-

>. " :-

/. " :-

(. " :-


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What causes all sounds?

A. 8ibrations

>. 6eflections

/. 6efractions

(. :eat


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Which of the following can sound not

travel through?

A. 7iquid

>. 8acuum

/. #olid

(. 9as


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Which of the following is not a use

of ultrasound?

A. *renatal scanning

>. Fuality control in industry

/. /leaning delicate machinery

(. /oo!ing food

&0 Fuestions


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&0 Fuestions

1' 0atch up the following parts of the electromagnetic

spectrum with their uses $

9amma rays Allow us to see

6adio waves 6emote /ontrols

Ultra 8iolet G#ee2 bro!en bones

8isible /arry +8 signals

0icrowaves 6A(A6

X rays #terilise equipment

nfra 6ed /auses sun)tans

&0 F ti


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&0 Fuestions

"' Which radiations are missing from below?

9amma A Ultraviolet 7ight nfrared > 6adio waves

A. ===========

>. ===========

X rays

0icrowaves

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Physics Revision Lesson 2