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Physics in concert

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Objectives

To understand how engineers use physics to set up a concert

LightingElectricitySound

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Microphone

Amplifier

Mixing desk

SoundA sound-system increases the volume of the sound.

Speaker

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Sound-systemA microphone is used to turn the sound wave from the music on the stage into an electronic signal.

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Sound-system

The electronic signal is sent via a mixing desk to the amplifier, which boosts the signal.

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Sound-system

The signal is turned back in to a (louder) sound by the speakers.

Ear

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Sound-pitch

Different musical instruments have different pitches.

High pitch

Low pitch

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Sound-pitch

High pitch sounds have a higher frequency

High pitch

Low pitch

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Signals for three different sound waves are shown below.

(i) which signal is from the loudest sound?

(ii) which signal is from the highest pitch sound?

Q1Q1

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Sound levels

• Sound levels are measured in decibels (dB)

Safe noise exposure

Hours Sound Level (dB)

8 85

4 90

1 100

1/4 110

0 120

120 dB or above can lead to instant hearing damage

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Sound-speed

Sound travels to the audience at a speed of 330 m/s

Speed = distance ÷ time

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Sound at a concert

The speed of sound is 330 m/s. How long it takes sound to travel 40 m?

Q2

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Lighting at a concert

Red, green and blue are used for stage lighting.

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Lighting at a concert

Red Green

Blue

Cyan

Yellow

Magenta

Other colour effects can be produced by mixing these three lights.

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Lighting at a concert

The colour an object appears depends on the colours it absorbs or reflects.

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Lighting at a concert

The colour an object appears depends on the colours it absorbs or reflects.

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Lighting at a concertAn artist on stage wears a red T-shirt with a yellow star

motif, and blue trousers.

Complete the table showing how his costume appears under different colour lighting.

Q3

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Lighting at a concert

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Lighting at a concert

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Lighting at a concert

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Lighting at a concert

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Lighting at a concert

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Lighting at a concert

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Review: Colour mixing

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Making electricity

The electricity for outdoor concerts needs to be produced on-site using a generator.

Generator

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Supplying electricity

Thick cables are used to carry large electrical currents to the sound and lighting systems.

Plug-in points for sound or lighting equipment

Generator

Electrical cables

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Electrical current

The larger the current, the thicker the cable needed.

The current in the cables can be calculated using the relationship

current = power ÷ voltage

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Electrical currentA lamp with a power rating of 100 W. Calculate

the current that flows when it is connected to a 240 V supply.

Q4

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Electrical circuits

• The lighting and sound systems are connected in parallel to the generators

Generator

Lamp 1

Lamp 2

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Electrical circuitsExplain the difference between a series and

parallel circuit

Q5

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Engineers at a concert

Sound Engineer Electrical Engineer Lighting Engineer

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Choose an artist

• Each person in your team will take on a different role

• But first you must choose the artist or group you will represent…

2 minutes

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Select your role by looking at the key skills:

1Creative

Analytical

Visual

2Analytical

Using diagrams

Numerical

3Spatially aware

Analytical

Numerical

2 minutes

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Your role:

1

Lighting engineer

2Electrical engineer

3Sound

engineer

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Practice your skills

• Complete the practice your skills worksheet that goes with your role

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Planning a concert

Sound Engineer Electrical Engineer Lighting Engineer

• You will need to complete the task and poster sheet that goes with your role

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Artist requests

• Check the card to see what your artist has requested.

Sound Level

Performance area

Satellite speaker distance

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Sound engineers

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Lighting engineers

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Electrical engineers

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