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Physics Topic 2
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- 1Label a Wave.Enter text here...
- 2When waves travel through a medium what happens?The particles vibrate and transfer energy and information between each other. But overall, the particles stay in the same place
- 3What is the amplitude of a wave?The displacement from the rest position to a crest or trough
- 4What is the wavelength of a wave?The length of a full cycle of a wave
- 5What is the frequency of a wave?The number of complete cycles of the wave passing a certain point per second
- 6What is the period of a wave?The number of seconds it takes for one full cycle
- 7Equation to work out the period of a wavePeriod = 1 / Frequency
- 8What type of vibrations do transverse waves have?Perpendicular / Sideways
- 9Examples of Transverse wavesAll electromagnetic waves
S-Waves
Ripples and waves in water - 10What type of vibrations do longitudinal waves have?Parallel
They are parallel to the direction in which the waves travel - 11Example of a longitudinal waveP-waves
- 12Longitudinal waves do what when they pass through the mediumSquash up and stretch out the arrangement of particles.
- 13What is wave speed?Tells you how quickly a wave moves through space
- 14Equation to work out wave speedWave speed = distance / time
- 15Another equation to work out wave speedWave speed = frequency x wavelength
- 16What do you use to measure the speed of a sound?An oscilloscope
- 17How do you use an oscilloscope to measure the speed of sound?- Set up the oscilloscope so detected waves at each microphone are shown as separate waves
- Start with both microscopes next to the speaker then slowly move away until two waves are aligned on the display but have moved exactly one wavelength away
- Measure the distance between the microphones to find out the wavelength
- You can then use the formula speed = frequency x wavelength. - 18How do you measure the speed of water ripples?Using a strobe light
- 19How do you measure the speed of water ripples using a strobe light?- using a signal generator attached to the dipper of a ripple tank can create water waves at a set frequency
- Dim the lights and turn on strobe light
- Freeze the screen and count how many shadows appear.
- Work our the average wavelength
- use Frequency x wavelength to work out the speed of the waves - 20What do you use to find the speed of waves in solids?Peak Frequency
- 21What happens to waves when they try to cross a boundary?Absorbed
Transmitted
Reflected - 22How is the wave absorbed?The wave transfers energy to the material’s energy stores. Often the energy is transferred to a thermal energy store which leads to heating
- 23How is a wave transmitted?The wave carries on travelling through the new material. This often leads to refraction. This can be used in communications as well as in the lenses of glasses and cameras
- 24How is a wave reflected?This is where the incoming ray is neither absorbed or transmitted but instead is ‘sent back’ away from the second material. This is how echoes are created
- 25How does sound travel?As a wave
- 26How are sound waves caused?By vibrating objects
- 27How are the vibrations passed?Through the surrounding medium as a series of compassions and rarefactions. Sound waves are a type of longitudinal waves.
- 28What is ultrasound?Sound waves above 20,000 hertz
- 29What can happen to ultrasound waves at boundaries?They can get partially reflected
- 30How can an ultrasound wave get partially reflected at boundaries?When a wave passes from one medium into another some of the wave is reflected off the boundary between the two media and some is transmitted and refracted this is partial reflection. The time it takes for the reflections to reach a detector can be used to measure how far away the boundary is
- 31Uses of UltrasoundMedical Imaging and Industrial Imaging
- 32Medical Imaging - UltrasoundUltrasound waves can pass through the body but whenever they reach a boundary between two different media some of the wave is reflected back. The extract timing and distribution of these echoes are processed by a computer to produce a video image of the foetus
- 33Industrial Imaging - UltrasoundCan be used to find flaws in pipes or materials such as wood or metal. Ultrasound waves entering a material will usually be reflected by the far side of the material. If there is a flaw such as a crack inside the object the waves will be reflected sooner
- 34What are infrared waves?Sound waves so low in frequency that we can’t hear them - they’re under 20 hertz
- 35What do some animals do with infrasound?Communicate - for example whales and elephants. By detecting infrasound scientists are able to track these animals for conversation purposes
- 36What else produces infrasound?Natural events like erupting volcanoes, avalanches and earthquakes. Scientists can monitor infrasound to try to predict events - like if a volcano will shortly erupt
- 37What are the main two seismic waves?P-waves and S-waves
- 38By investing how seismic waves are absorbed and refracted, scientists have been able to work out what?Where the properties of the earth change dramatically.
- 39Differences between p-waves and s-waves- P-waves are longitudinal and s-waves are transverse.
- p-waves travel through solids and liquids, whereas a-waves only travel through solids
P-waves are faster than a-waves - 40What does the law of reflection show?Angle of incidence = angle of reflection
- 41What is the angle of incidence?The angle between the incoming wave and the normal
- 42What is the angle of reflection?The angle between the reflected wave and the normal
- 43What is the normal?An imaginary line that’s perpendicular to the surface at the point of incidence
- 44What can reflection be?Specular or diffuse
- 45What is specular reflection?When waves are reflected in a single direction by a smooth surface
- 46What is diffuse reflection?When waves are reflected by a rough surface and the waves are reflected in all directions
- 47What is colour about?Differences in absorption, transmission and reflection of different wavelengths by different materials
- 48What is white light?A mixture of all the different colours of light, which all have different wavelengths
- 49From red to violet what happens with wavelength and frequency?Long to short wavelength and low to high frequency
- 50What are opaque objects?Objects that don’t transmit light. When visible light waves hit them, they absorb some wavelengths of light and reflect others
- 51What can white objects do?Reflect all wavelengths of visible light equally
- 52What do black objects do?Absorb all wavelengths of visible light. Your eyes see black as the lack of any visible light
- 53What do transparent and translucent objects do?Transmit light
- 54What two types of images can be formed by lenses?Real and Virtual
- 55How is a real image formed?When the light rays actually come together to form the image. The image can be captured on a screen because the light rays actually meet at the place where the image seems to be
- 56How is a virtual image formed?When the light rays from the object appear to be coming from a completely different place to where they’re actually coming from. The light rays don’t actually come together therefore cannot be captured on screen
- 57What is focal length?Related to power of the lens. The more powerful the lens, the more strongly it converges rays of light, so the shorter the focal length
- 58Is the power positive or negative for a converging lens?Positive
- 59Are electromagnetic waves transverse or longitudinal?Transverse waves
- 60How do electromagnetic waves travel?Through a vacuum
- 61What are the 7 groups in the electromagnetic spectrum?Radio Waves
Microwaves
Infrared
Visible Light
Ultra Violet
X-Rays
Gamma Rays - 62Wavelength for different groups in electromagnetic spectrumRadio - 1m-10^4m
Microwaves - 10^-2
Infrared - 10^-5
Visible Light - 10^-7
Ultraviolet - 10^-8
X-rays - 10^-10
Gamma Rays 10^-15 - 63What are all objects continually doing?Emitting (radiating) and absorbing EM radiation
- 64What does the distribution and intensity of these wavelengths only depend on?The object’s temperature. Intensity is the power per unit area
- 65As the temperature of an object increases what happens?The intensity of every emitter wavelength increases. However, the intensity increases more rapidly for shorter wavelengths than longer wavelengths. This causes peak wavelength
- 66What does radiation affect?The Earth’s temperature
- 67The overall temperature of the earth depends on what?The amount of radiation it reflects, absorbs and emits
- 68What are radio waves mainly used for?Communication and broadcasting
- 69What are microwaves and radio waves used by?Satellites
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- GCSE Physics Karteikarten am Physics Topic 2, erstellt von Harry Smith am 19/11/2018.
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