Waves and Energy

Waves and EnergyYear 9Ms Gibellini SLOs

SLODefine EnergyName common forms of Energy

EnergyWhat is energy? Can we see it? What does it do?

Energy is the ability to do workWe cannot see energy but substances and objects can have energyAll energy originally comes from the sun

you have energy from your food and you use it to grow and move and think

a moving car has energy from petrol and they use it to moveradios from electricity and it uses it to make a sound

a glowing torch has energy from chemicals in a battery and it uses it to make light

Types of Energy

/Stored/Active

Success CriteriaComplete cut and paste of Energy Types

Complete Sci pad page 74 Introduction to Energy

List five things that energy can do?Powers appliances, causes movement, creates light, heat and soundWhere does all energy come from?SUN!Where do you get energy for your body from?The food we eat CHEMICAL ENERGY

SLODescribe energy Transformations

Describe the Law of Conservation of EnergyLaw of Conservation of EnergyEnergy can neither be created nor it is destroyed, however energy can be converted from one form of energy to any other form of energyEnergy ChangesTo describe an energy change for a light bulb we need to do 3 steps:Electricity Light + heat1) Write down the starting energy:3) Write down what energy types are given out:2) Draw an arrow

What are the energy changes for the following?An electric fire A rock being dropped from a cliffAn arrow being firedEnergy ChainsWhat are the energy changes for the following?An electric fire Electricity Heat + light

A rock dropping from cliffGravitational kinetic sound + heat

An arrow being fired?Elastic + gravitational kinetic heat + sound

Energy ChainsItemEnergy InEnergy OutEnergy ChainBalloon CarElasticKinetic, sound, heatDinosaurBow and ArrowSolar LightYo yoMouse trapSlinkyCap bombItemEnergy InEnergy OutEnergy ChainWindmillTuning forkBallTeethFanCarsShaker ItemEnergy InEnergy OutEnergy ChainWindmillKinetic kinetic + heatTuning forkKinetic kinetic + sound + heat BallGrav. kinetic sound + heatTeethKinetic elastic sound + heat + kineticFanChemical electrical kinetic + heat + sound+ lightCarsKinetic elastic kinetic + sound + heatShaker Grav. + kinetic sound + heat + kineticRace CarKinetic Chemical electrical sound + heat + lightSuccess CriteriaComplete worksheets on energy chains

Where does all energy originate from?SUNDraw an energy chain for the human eye.Light energy electrical energy chemical energyDescribe the energy transformations taking place as a plane takes offChemical electrical kinetic + sound + heat gravitational + sound and heatComplete page 79 of Sci pad Energy Transformations and 77 energy changes in an engine

t18SLODescribe energy efficiency and calculate efficiency of appliancesEnergy Efficiency We know that not all energy is used by appliances:E.g. Light bulbElectrical energy Light energy + heat energyLight energy is useful energy, but in the case of a light bulb heat energy is wasted energy.

Question:Give an energy transformation for an electric stove element.Name the useful in an electric stove element.Name the wasted energy in an electric stove element.

Walnut EnergyThe scientific unit for energy is the joule (J).1,000 J = 1kJ,kJ = kilojoulesIf you heated 1 ml of water by 1C, then the water would gain 4.2 joules of heat energy.We can use this to figure out how much energy 1 peanut has in joules.

Walnut EnergyAim: To find out how much energy is in a walnut

Method:

Results:

Energy Supplied by Peanut: B-A

Conclusion:

Which food had more energy in it?walnutWrite an energy chain for these experiments.Chemical heat + lightNot all the energy is used to heat the water, what is it wasted as?Light energy

FoodTemp AfterATemp BeforeBChange in TempA -BX 42Energy in JoulesWalnutMarshmallowJelly beanWe use the following equation:

Useful Energy = energy input wasted energy

From this we can calculate the ENERGY EFFICIENCY of an appliance:ENERGY EFFICIENCY = USEFUL ENERGY X 100 ENERGY INPUTThis gives us the energy efficiency as a percentage %.

e.g.A radio is supplied with 3500J of electrical energy. 3000J is released as sound energy; the rest is lost as heat energy.What is the energy efficiency of the radio?Step 1: Write out the information you have:Energy Input = 3500J Useful Energy = 3000J Wasted E = 500JStep 2: Write out the equation:ENERGY EFFICIENCY = USEFUL ENERGY X 100 ENERGY INPUT

Step 3: Substitute in the numbers from Step 1:ENERGY EFFICIENCY = 3000J X 100 3500JENERGY EFFICIENCY = 85.7 % round up to 86%

Questions:1. A light bulb is supplied with 60J of electrical energy every second. It transforms about 20J into light and the remaining 40J into heat. What is the energy efficiency of the light bulb?2. An electric motor transforms 1600J of the 2000J is supplied with into useful work. The rest is dissipated as heat. How efficient is the motor?3. A car, when supplied with 250kJ of energy, converts 75kJ into kinetic energy in the engine, the rest is dissipated as heat and sound energy. What is the energy efficiency of the cars engine?4. An electric hairdryer is supplied with 4500J of electrical energy. 3000J of this energy is released as heat and kinetic energy to dry hair with, the rest is released as sound and some light. What is the energy efficiency of the hairdryer?

Success CriteriaComplete pages 76 of Sci pad wasted energy

For every 100 Joules of energy used by an electric light bulb you get only 15 Joules of light energy.

What happened to the other 85 joules of energy?Wasted as heat energy

b) What is the % efficiency of the light bulb?Eff = useful/total energy x 100 = 15/100 x100 = 15 %

SLODefine a wave and describe two common formsLight and Sound wavesLight travels in a straight line

Sound is a vibration, longitudinal wave

Light travels faster than sound,Sound =770 miles per hour650,500,000 miles per hour in air lightening and thunderFireworks

Types of WavesTransverse Waves:Light, up and down or side to side

Longitudinal Sound waves vibrations are along the same direction as the direction of travel. (in and out)

VibrationsHow are sounds made?Particles moving (vibrating)

How does sound get from the source (say, the teacher's mouth) to your ears?By vibrating air particles moving from the source (mouth) to your ears and banging into your ear drum

How can we stop sounds?Stop vibrating, stop particles from reaching your ears (ear muffs), soft furnishings to absorb sounds (vibration) and stop them reflecting back into the room

Sound waves cannot be heard in space (vacuum, no particles) because.?Need particles to vibrate, no particles in space!

Success CriteriaComplete scipad page 78

How are sound waves made? What do they need?When something vibrates, they need a medium (gas, air) to move through. Need particles to vibrate.

What type of wave are sound waves?Longitudinal

What type of wave are light waves ?Transverse

SLOIdentify the amplitude, frequency and wavelength of waves

Define and describe sound waves in terms of pitch and loudnessWaves

Amplitude and Frequency

37Pitch = FrequencyPitch is determined by the wavelength

The number of wavelengths passing a point every second is called Frequency, measure in Hertz

Longer the wavelength lower the pitch

Shorter the wavelength higher the pitch

Loudness = AmplitudeThe amplitudeof a sound wave is related to the energy (loudness and softness) that the wave carries, measured in decibels.

The stronger the vibration the greater the sound energy

Reading waves

WavePitch (high/Low)Loudness(loud/quiet)ABCDReading waves

WavePitch (high/Low)Loudness(loud/quiet)ALowloudBLowQuietCHighLoudDHighQuietReading wavesWave A and B have the same frequency, but A is louder.Waves A and B have the same pitch.Waves C and D have the same frequency, but C is louder.Waves C and D have the same pitch.

28/05/2015Using an oscilloscope1) Quiet sound, low frequency:2) Quiet sound, high frequency:3) Loud sound, low frequency:4) Loud sound, high frequency:Success CriteriaComplete pages 78-81

What affect does increasing the amplitude have on sounds?LouderWhat effect does increasing the frequency have on sounds?Wavelength is shorter, sound is higher pitchedHow does changing the pitch effect frequency and sounds?Lower or higher depending on wavelength, greater the pitch greater the frequencyDraw a labelled diagram to show a wavelength and amplitude on a sound wave.How do we calculate Hertz?Number of wavelengths passing a point every second

SLODraw the basic structure of a human earWhat did the receiver say to the radio wave? Ouch! That megahertz.28/05/2015How sound travelsAs we know, sound waves are formed when something vibrates. But how does the sound reach our ears?

1) An object makes a sound by vibrating2) The vibrations pass through air by making air molecules vibrate3) These vibrations are picked up by the earAir molecules28/05/2015How does the ear work?

1) Sound waves are funnelled into the ear by the pinna4) These vibrations are turned into electrical signals in the cochlea2) These vibrations make the ear drum vibrate3) These vibrations make the ear bones vibrate5) The electrical signals are then sent to the brain

Ears and Hearing

The Ear

https://www.youtube.com/watch?v=HMXoHKwWmU8

HearingSomething vibrates and creates asound wave.The sound wave travels to the ear and is collect by theouter ear.The sound wave then moves into theear canal.When it reaches the end of the ear canal, the sound waves bump up against the eardrum.The ear drum vibrates with these sound waves.The vibration movestiny bones in the middle ear.These bones carry vibrations into the inner ear to a fluid-filled tube called thecochlea.The fluid inside the cochlea vibrates a series of tiny hairs called cilia, which are attached to auditory nerves.The movement of these cilia stimulates thenerve cells, and they send signals to the brain via the auditory nerve.The brain processes these signals into the sounds we hear

Success CriteriaComplete Scipad pages 78-82 on Waves and Sound

Draw a flow diagram to show how the human ear works (how sounds move from outer ear to brain, and what kind of energy forms they change to)

Draw a labelled diagram of the ear, what effect does increase the pitch have on the ear drum? What about increasing the amplitude?

Hearing Simplified Sound vibrations enter Pinna ear canal ear drum hammer anvil stirrup semi circular canal cochlea Cilia nerve brainSLODescribe some properties of light and give some examples

LightMake a list of all the things that we use light for

help us see things, can burn us, creates rainbows,helps plants produce food photosynthesishelps us take photosreflects - mirrorscan be hot or cold

Properties of lightThe light has three distinctive properties:moves in a straight line.

It reflects when it reaches a reflecting surface.

Changes direction as it passes from one medium to another (is refracted).

Se refleja cuando llega a una superficie reflectante.Cambia de direccin al pasar de un medio a otro (se refracta).57

Sources of LightList as many sources of light as you can.Light sources can be grouped:Incandescent Sources:Light produced by heat.flamelight bulbsparksbar heaterstarslightningCold Light:glow worms, fire fliesphosphorescence TV monitors, fluorescence tubesfluorescence clock faces, glow in the dark thingsluminescenceReflected LightThe moon reflects the suns light, it does not emit it is own light.We see other objects that are not light sources, because light rays from other sources bounce off them in all directions. ( Light is reflected)

Success CriteriaComplete scipad 83 - 84

SLODraw ray diagrams and use them to explain shadowsBBCBBC bitesize

Puppet clipShadowsA region without light is called a shadow.The shape of the shadow may not be identical to the shape of the object because the shadows shape depends on the position of the light source and on where the shadow falls.The size and intensity of the shadow depends on the size of the light source and the distance between the light source and the object.

Success CriteriaMake a shadow head of yourself, make it a big warped so it looks funny by playing with the angles

Complete page 85-86 of scipadhttp://www.youtube.com/watch?v=NZ5MJqB9myA

SLOObserve reflection and use the Laws of Reflection to explain observationsMeasure and record anglesIdentify and make predictions from patterns in data

Reflection

What is it about objects that let us see them? Why do we see the road, or a pen, or a best friend? If an object does not emit its own light (which accounts for most objects in the world), it mustreflectlight in order to be seen.

ReflectionThe angle of reflection always equals the angle of incidence.

The normal is an imaginary line at right angles (90 degrees) to the point where the incident ray hits the mirror.

Drawing Ray Diagram RulesRulerPencilStraight lines, with arrowsNo sketchingLines on back of mirrorLight box at correct angleCorrect number of rays

Success CriteriaComplete Page 87 of scipad

Draw a diagram to show how a periscope works (remember your eyes do not emit light so have the arrows going the correct direction and light travels in straight lines so use a ruler!)

SLODescribe various uses of reflective surfaces

Observe the effect of convex and concave mirrors on rays of lightUses of Reflective SurfacesWhere are mirrors used?PeriscopesCarsSatellitesFibre opticsphotography

How are they used? VideoCurved MirrorsConcave mirrors cause the light rays to converge together:

Convex mirrors cause light rays to diverge

Rays and Angles

Incidence RayReflected Ray

Success CriteriaComplete scipad page 89-91

Complete the following ray diagrams, label the mirrors as well.

Video

SLOObserve refraction and explain your observations

Investigate refraction in lenses of various shapesRefractionPut the coin in a beaker, hold a ruler vertically on a bench.Put your eye at the zero mark on the ruler and get your partner to move the beaker away until you can see to coin (over the lip of the beaker).Slowly add water to the beaker, what happens to your view of the coin?Move your eye down towards the bench until you can see the edge of the coin again.How far down did you have to move?What has happened? Why?

RefractionThe bending of light is called refraction.Light bends when it passes through substances of different densities. (air to water, air to glass)The more dense a substance the more it bends

Refraction In LensesLensesLenses are curved pieces of glass or plastic

Convex lenses cause rays to converge (come to a point)

Concave lenses cause rays to diverge (go away from each other.

Success CriteriaWhat is the difference between refraction and reflection, draw a diagram to illustrate your answer.

Reflection light rays bounce off,Refraction the light rays are bent as they go from one medium to another

What do we call it when light bends as it passes between mediums?

The light rays entering an leaving a glass block should be?parallel

Complete pages 92-95 of Scipad

SLOInvestigate the appearance of coloured objects

Dispersion of ColoursVisible or White light is made up of 7 different colours ROYGBIVDifferent colours have different wavelengths (distance between two peaks)We can only see the visible part of the electromagnetic spectrum(all of the different lengths of waves)

Dispersion of colour

We can split white light into its different parts using a prism, this is called Dispersion. (water can do this to form a rainbow)

Different colours have different wavelengths so travel at different speed through glass or water, therefore they refracted (bent) different amounts, and therefore dispersed (spread out).

Seeing colourWhy is a leaf green, milk white and a tomato red?When white light hits an object most wavelengths are absorbed, the one colour that is reflected is the colour of the objectA green leaf reflects green light and absorbs all other colours, hence it appears green

Seeing colourExplain why milk is white and a tomato is red.

Milk reflects all colours, so appears white

Tomato absorbs all colours except red, it reflects red to your eye so looks red!

Mixing ColoursRed, yellow and blue are called the primary colour lights.

We can use these three colours to make many different colours.

Light PracticalsWhite light is made up of a mixture of colours (ROYGBIV). A coloured filter will let through some of the colours and stop others.

Which filters will let through?Red red, magentaGreen Green, cyanBlue blue, magenta, cyanYellow yellowMagenta (red and blue) Red, blueCyan (blue & green) Blue, greenPredict what colours will get though when:

Light that passes through a primary red filter hits a primary blue filter. - magenta

Light that passes through a primary red filter hits a primary green filter. black

Light that passes through a primary green filter hits a primary blue filter. cyan

Now carry out experiments to test your predictions.

Success CriteriaComplete scipad pages 100-102Why does white paper still appear white even though the white light shining on it is made up of ROYGBIV?Colours are all squashed together so appears whiteWhat is the name given to the part of the electromagnetic spectrum that we can see? visibleWhen white light passes through a green filter what colour do we see? GreenWhy do we see a spectrum of different colours when white light is shone through a prism and not just a white spot?White light is made up of ROYGBIV and the prism bends them all by a different amount so we see themWhat do we see when we shine red light onto blue paint?MagentaWhy do leaves look green?Because white light is made up of ROYGBIV and leaves absorb ROYBIV and reflect Green light to your eyes!

SLODescribe the basic structure and function of the human eye

Structure of the Eye

How our eyes workLight enters the eye through the cornea and pupil

The light is focused onto the back of the eye (retina) by the lens

The retina is covered in light sensitive cells called light receptors

The receptors change the light energy into electrical energy and a message is passed from the optical nerve to the brain

http://www.e-learningforkids.org/Courses/Liquid_Animation/Body_Parts/Vision/index.html

https://www.youtube.com/watch?v=syaQgmxb5i0

How we See

Seeing ColourCones see colourHumans have three different types of cones, red, blue and green

Success CriteriaComplete page 96-99 of scipad

Describe the following terms, use diagrams to help: colour blindness, short sighted, long sighted

Revisionhttps://www.youtube.com/watch?v=CbkaL-vgiKI