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Sound

Objectives

Be able to describe what a sound is and how its pitch can be altered.

HSW: AF4 – Using investigative approaches

Used before in: Will use again in:

PLTS: Team Workers: collaborate with others to work towards a common goal.

Used before in: Will use again in:

18 April 2023

KeywordsInfrared, visible, EM Spectrum, remote control, digital,

photography.

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OUTCOMES

• ALL MUST be able to describe what a sound is.

• The pitch of a note increases as the frequency increases.

• The loudness of a note increases as the amplitude of the wave increases.

• MOST SHOULD know how to compare the amplitudes and frequencies of sounds from diagrams of oscilloscope traces.

• SOME COULD be able to explain how the design of musical instruments affects their sound and pitch.

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SOUND Starter

KEYWORD SCRAMBLE: UNSCRAMBLE THE WORD AND WRITE A DEFINITION. THE FIRST PERSON TO DO THE MOST IN 6 MINS WINS)

WORD Definition

vbiaritons

ncyquefre

ztreh

waltenvegh

plitudeam

deeps

osiclolcospe

tongillunida

pierod

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Word Definition

Vibrations A movement of a particle about a fixed point

Frequency The amount of vibrations in a second

Hertz The unit of frequency (same as 1/s)

Wavelength The distance between to consecutive similar points on a wave (ie peak to peak)

Amplitude The distance from the centre to the peak or trough of the wave. (the loudness)

Speed The distance an object travels in a given time

Oscilloscope A device that can show electrical signals on a screen

Longitudinal A wave where the particles travel parallel to the direction of the wave.

Period The time for one wave in seconds (1/frequency)

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Introduction

• http://www.ltscotland.org.uk/5to14/resources/science/speedofsound.asp Show the speed of sound animation. What would happen if I hit it harder? Would it go quicker? Show: http://www.ltscotland.org.uk/5to14/resources/science/sound/soundpulse.asp to explain.

• What is a sound wave? • Demo how to make some different sounds. • Demo a speaker cones vibration with rice on it. • Connect it to a signal generator in order to get different pitches and

see what is happening. Demo slinky.• Look at sound waves in solids and gases:

http://www.ltscotland.org.uk/5to14/resources/science/sound/index.asp and then

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Studying waveforms in the classroom

An oscilloscope is an instrument that detects a varying voltage from an input, such as a microphone, and plots its waveform against time.

A signal generator produces an alternating voltage at a chosen frequency and amplitude.

It can also produce a range of different waveforms.

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Using an oscilloscope

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• Demos

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Understanding waves and waveforms

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Straw Oboe

Flatten one end of the soda straw by sticking the end in your mouth, biting down with your teeth and pulling it out. Do this several times to make a nice flexible flat ended straw.Cut a piece of straw from each side of the flat region making the straw have two lips at the end.

Cut two edges off the flattened end of a straw.Put the straw in your mouth, bite down on it gently with your front teeth just beyond the cut end.

Bite down with your teeth just beyond the cut end of the straw.Experiment with blowing hard and soft while biting down hard and soft until you make the straw sing.

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Plenary

• Vibrations cause sound as a ………….. wave.• The speed of sound in air is ……m/s.• Sound travels faster in ………. and faster again

in solids because the particles are ……….. together.

• Since it is a wave it can be reflected (echo) and ………….

• Sound cannot travel through a ……. (In space nobody can hear you scream.)

• If the frequency is higher the ………. is too.