Waves- Paper 2 Flashcards
How do waves transfer energy?
.Waves travel through a medium, the particles of the medium oscillate and transfer energy between each other
Amplitude?
wave is the maximum displacement point on the wave from its undisturbed position.
Wavelength?
.distance between the same point two adjacent waves
Frequency?
.number complete waves passing certain point per second.
Frequency measured in hertz (Hz). 1 Hz is I wave per second.
period of a wave and a period equation?
.find period of a wave using: amount of time it takes for a full cycle of the wave and frequency.
Period (s)=1/frequency (HZ)
Transverse waves: how do they oscillate?
What waves are transverse?
1.oscillations are perpendicular direction of energy transfer.
2.Most waves are transverse:
All electromagnetic waves, waves in water
Longitudinal Waves oscillations?
What types of waves are there
.oscillations parallel to direction energy transfer.
.Sound waves, ultrasound.
What is wave speed?
What is the equation for wave speed?
.wave speed: speed at which energy is being transferred
.wave speed (m/s)= frequency (HZ)x wavelength (m).
How to use Oscilloscope to Measure the Speed of Sound?
1)attaching signal generator speaker=generate sounds specific frequency
2) Set up oscilloscope so detected waves each microphone shown as separate waves.
3)Start both next to the speaker move slowly away the two waves alone display one wavelength apart.
4)Measure distance between microphones one wavelength.
4) wave speed (m/s)= frequency (HZ)x wavelength (m)
5) speed sound in air 330 m/s
How to Measure the Speed of Water Ripples Using a Lamp? 6
- Ripple tank depth 5mm
2.dipper signal generator attached know frequency
3.screen below and a dim light
4.shows the patterns of the ripples
5.distance with the ruler each shadow line 10 wavelengths
Apart with a metre ruler
6.Then divide by 10 for average one wave length
=improve accuracy take digital photo shows use that measure 10 waves lengths
How to use Wave Equation for Waves on Strings? 4
1)Attach a string vibration signal generator-200 gram (g) hanging mass pulley=taut
2)Switch vibration generator=stationary waves can be clearly observed.
3)Measure length half wavelengths (loops) as possible, divide by number of half wavelengths=half wavelength, doubling= wavelength.
4)frequency power supply=wave speed = frequency × wavelength.
When waves arrive at a boundary between two different materials, three things can happen and why?
1)waves absorbed= material wave cross into - this transfers energy materials energy stores- matt
2)waves transmitted=waves carry on travelling through new material=refraction.
3) waves reflected= bounce back- shiny depends wavelength wave, properties of the materials involved
1)What is the angle of incidence and what is the one important rule?
3) what is the angle of reflection?
4) what is the normal?
1)Angle of incidence = Angle of reflection
angle of incidence= angle between incoming wave and the normal.
3)angle reflection=angle between reflected wave, normal.
4)normal=imaginary line perpendicular surface point of incidence (wave hits the boundary). dotted line.
1)How and why Reflection can be Specular or Diffuse?
2) Specular reflection?
3) diffuse reflections?
1)Waves are reflected different boundaries different ways, the normals will be different
2)Specular reflection=wave is reflected in single direction by smooth surface all normals are the same
3)Diffuse reflection=wave is reflected by a rough surface and reflected rays are scattered lots of different directions. normal is different for each incoming ray=angle of incidence is different.= not clear matte surface no reflection
Diffuse diagram?
Specular diagram?
How do lenses form images and the two types?
-Lenses form images by refracting light
two main types lens - convex and concave.
What is the axis of a lens?
.axis of a lens is a line passing through the middle of the lens.
Why do Different Lenses Produce Different Kinds of Image? 3 per lens
1) convex lens
-bulges outwards.
-causes rays of light parallel to the axis (converge) at the principal focus.
1)concave lens
-caves inwards.
-parallel rays of light to spread out (diverge).
-principal focus of a concave lens is the point where rays hitting the lens parallel to the axis,trace them back until they all appear to meet up point behind lens.
What is the focal length?
. principal focus on each side of the lens= distance from centre of the lens to the principal focus= focal length.
What are the colours of visible light?
Roygbv= red orange yellow green blue violet
What are the Three Rules for Refraction in a Convex Lens?
1) incident ray parallel axis refracts lens, passes through principal focus other side.
2) incident ray passing principal focus, refracts through the lens and travels parallel to the axis.
3) incident ray passing through the centre of the lens carries on in the same direction.
what are Three Rules for Refraction in a Concave Lens?
1) incident ray parallel to the axis refracts through lens, travels in line with the principal focus
2) incident ray passing through the lens towards the principal focus refracts through the lens and travels parallel to the axis.
3) incident ray passing through the centre of the lens carries on in the same direction.
Concave lens and convex lens?
What is a real image an example?
.where the light from an object comes together to form an image on a ‘screen’ - like image formed on eye’s retina
What is a virtual image and example?
.when the rays are diverging, light from object appears to be coming from a different place.
. Mirror virtual image of your face because the object appears to be behind mirror.
-magnifying lens
How To describe an image properly, you need to say 3 things?
1) How big it is compared to the object;
2) upright or inverted (upside down)
3) real or virtual.
How to Draw a Ray Diagram for an Image Through a Convex Lens?
1)Pick a point on the top of the object. Draw a ray going from the object to lens parallel to the axis of the lens
2) Draw another ray from the top of the object going right through the middle of the lens.
3) incident ray that’s parallel to the axis is refracted through the principal focus (F) on other side of the lens.Draw a refracted ray passing through principal focus.
4) The ray passing through the middle of the lens doesn’t bend
5) Mark where the rays meet (top of the image.)
6) Repeat the process for a point on the bottom of the object. When bottom of the object is on the
axis, the bottom of the image is also on axis.
How does Distance from the Lens Affects the Image? 2F, F and between
1) 2F= real, inverted image the same size as the object
2) Between F and 2F=real, inverted image bigger object, beyond 2F.
3) F= virtual image, right way up, bigger object, same side of the lens.
How to Draw a Ray Diagram for an Image Through a Concave Lens?
1)Pick a point on the top of the object. Draw a ray going from the object to the lens parallel to the axis of the lens.
2) Draw another ray from the top of the object going right through the middle of the lens.
3) The incident ray that’s parallel to axis is refracted so appears come from principal focus. Draw a ray from the principal focus,dotted before it reaches the lens.
4)Ray passing through the middle of the lens doesn’t bend.
5) Mark where the refracted rays meet= top of the image.
6)Repeat the process for a point on the bottom object. bottom of the object is on the axis, bottom of the image is also on the axis.
Concave Lenses Always Create…. Image?
.concave lens always produces a virtual image.image is right way up, smaller than the object, on the same side of the lens as the object, no matter where object is.
Magnifying Glasses Use Convex Lenses?
1)Job=creating a magnified virtual image. How= closer to the lens than the focal length.
2) virtual image (can’t project) light rays don’t actually come place where image appears to be.
4) magnification= image height/ object height
Why does Colour and Transparency Depend on Absorbed Wavelengths?
Different objects absorb, transmit and reflect different wavelengths of light in different ways
What is Opaque, what colours, what do they reflect/absorb?
1)objects that do not transmit light.
2)visible light waves hit them, absorb some wavelengths of light, reflect others.
2) colour opaque object depends wavelengths of light are most strongly reflected. reflecting wavelengths of light corresponding to that colour
What is White and black what colours, what do they reflect/absorb?
-black= absorb all the wavelegnths of light
-white= reflcts all the wavelengths of light
What is Transparent and translucent what colours, what do they reflect/absorb?
1)Transparent (see-through) and translucent (partially see-through)
2) wavelengths light-not reflected or absorbed by an object= transparent. transmitted the light ‘see through’.
3)transmit some light but are not completely clear.
Why do Colour Filters Only Let Through Particular Wavelengths?
1.white light passes through a coloured filter, all colours are absorbed except for the colour of the filter.
E.g: orange filter transmits orange light but absorbs all the other colours. Only orange will show.
What happens when an object appears black?
1)if it absorbs all the wavelengths of visible light.
An object that appears blue in white light will appear black in red light.
Red light contains no blue light for the object to reflect.
How does the temperature of a given object change how much infraded radation is given off?
what does it mean if an object has a contsant temperature?
Does the colour of an object or the surafce amke a diffrence to wether the they absorb or emit more?
1)hotter object=more infrared radiation radiates
2)object hotter than its surroundings emits more IR radiation than it absorbs as it cools down.
3)object that’s cooler than its surroundings absorbs more IR radiation than it emits as it warms up
4)Objects=constant temperature emit infrared radiation same rate that they are absorbing it.
5)Some colours and surfaces absorb and emit radiation better than others.
What is a Leslie cube?
.hollow, watertight, metal cube made of aluminium, four vertical faces have different surfaces (matt black paint, matt white paint, shiny metal,dull metal).
You Can Investigate IR Emission With a Leslie Cube? 5
1)Leslie cube heat-resistant mat. boiling water.
2)one minute=surfaces to heat
3)infrared detector measure intensity of infrared radiation emitted from each surface.
4)detector same distance each surface for each reading- reaptable and fair
5) matt black emits the most, shiny black, white, shiny matellic
What can you also investigate with a Leslie cube and how? 3
1)absorption depends on surfaces.
2)stick ball the back of two different surfaces with wax
3)which one falls off first when surfaces placed equal distances Bunsen burner
What impacts wavelengths?
-intensity increases rapidly for shorter wavelengths
-very hot objects realise short wavelengths that’s why very hot objects produce visible light
How do sound waves travel?
Where do soundwaves travel the fatsest from? 3
how do sound waves travel through a soild?
Can sound waves travel through space?
1)Sound waves= vibrations passes medium compressions,rarefactions
2) Sound travels faster solids, liquids, gases.
3)sound wave travels through solid the particles in solid to vibrate.
4) Sound can’t travel in space- vacuum (there are no particles to move or vibrate).
What is the differences between P waves and S waves? 4
.P-waves can Travel through the Earth’s Core, S-waves can’t
.p waves= longitudinal, S waves= transverse
.p waves travel through solids and liquids, S waves only soilds
.p waves=fastest,
slower= p waves
How has observing seismic waves helped?
-observing how seismic waves are absorbed and refracted, properties Earth structural change.
What are short radio wave signals?
What is the ionosphere?
-received long distances from the transmitter
-reflected from ionosphere- electrically charged layer in earths upper atmosphere
How can you produce radio waves using AC? 3
-electrons oscillates to create radio waves= transmitter
1)transmitted radio waves reach a receiver radio waves absorbed
2)energy carried by the waves is transffered electrons in the material of the receiver
3)energy causes electrons to oscillate=generates AC
All the electromagnetic waves?
How to construct a ray diagram for refracted light ray?
- boundary between two materials, normal 90° to the boundary.
- Draw incident ray meets normal- protractor
- Draw refracted Ray other side boundary.
-optically denser than first=refracted ray towards normal angle between infracted and normal smaller angle of incidence.
-less optically dense= refracted away from normal angle= refraction larger angle then incidence.
How do you fibre optic cables work?
Why does light refract when traveling through the cables?
(Optic fibres) plastic fibre and visible light=data over distance
1. refract light bounced back and forth
2. Because: Light is not easily, absorbed, scattered when travelling among fibre.
Concave and conveys diagrams?
Convex= real or virtual
Concave= virtual
