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| Question | Answer |
| What are waves? | Waves transfer energy and information from one place to another. |
| What are the two types of waves? | Mechanical waves - need a material medium to travel through (solid, liquid, gas) Electromagnetic waves - Can travel through a vacuum |
| ................ and ...................... are transferred by waves without transfer of .................... . | Energy Information Matter |
| What are the two types of mechanical waves? Describe them. | transverse- the medium moves at right angles to the direction of motion of the wave Longitudinal (e.g. sound)- the medium moves in the same direction as the motion of the wave |
| What is wave length? | The distance between two corresponding points of similar displacement (e.g. one crest to the next crest) |
| What is amplitude? |
The maximum displacement of part of a medium from its rest point
Image:
amplitude (image/png)
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| What is a period? | The time for one complete cycle of the waveform |
| Waves What is frequency? How do you calculate it? What is it measured in? | The number of cycle of the waveform per second. frequency= 1/period Hertz (Hz) as long as the period is in seconds |
| How do you calculate the wave speed? |
Wave speed (m/s)= frequency (Hz) X wavelength (m)
Image:
wave_equation (image/png)
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Image:
waves (image/png)
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?= Displacement Notice the x axis! |
| What is diffraction? | Spreading of waves as they pass by the edges of obstacles |
| Draw 3 pictures to show diffraction when the a wave passes a) through a small gap b) passes around the edge of one obstacle that is at one side c)passes around the edge of one obstacle that is in the middle |
Image:
diffraction (image/png)
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| Diffraction occurs with ........... waves. Why can you hear someone calling you when you can't see them, but you can't see light 'always travels in straight lines?' | all The effect of diffraction is small when the gap size is large compared to the wavelength. The effect is much greater when the gap size is similar to the wavelength. Sound has a wavelength of about 1cm-15m whereas all light wavelengths are smaller than 1/1000 mm so diffraction effects aren't noticeable. |
| What are electromagnetic waves? | Transverse waves which do not use a material medium and all travel through a vacuum at the same speed |
| Electromagnetic spectrum in order of biggest wavelength to smallest wavelength (and smallest frequency to biggest frequency!) | Radio waves; Microwaves; Infrared; Visible Light; Ultraviolet; X-rays; Gamma rays Red Midgets In Venezuela Use Xylophone Gongs |
| Order of colours in the visible part of the EM spectrum | Red; Orange; Yellow; Green; Blue; Indigo; Violet Richard Of York Gave Battle In Vain |
| What are the uses of radio waves? | Communication of information e.g. speech, radio and TV, music and encoded messages like computer data, navigation signals, telephone conversations. Radio have lowest frequencies and longest wavelength, TV and digital communication uses higher frequencies and shorter wavelengths |
| What are the uses of microwaves? What are the dangers of microwaves? | Heating food- transferring energy to water content in the food Satellite communication and radar- detect aircraft and shipping heat internal body tissue- serous damage before pain is felt- microwaves have a cut-out which turn off the microwave radiation when the cooker door is opened |
| What are the uses of infrared? What are the dangers of infrared? | Heating devices and in night vision cameras- pick up different temperatures because the wavelength of infrared is shorter from warm objects than cool objects Readily absorbed by our skin and will result in burns- wear protective clothing with reflective surfaces and insulating properties |
| What are the uses of visible light? | Used by human to see, photography and in types of fibre optics to look inside the human body |
| What are the uses of ultraviolet? What are the dangers of ultraviolet? | Fluorescent lamps, disco lights, sterilising water, some insects can see into the ultraviolet spectrum and use this to navigate and identify food sources Skin cancer, damage the eyes. Sun is main source - protection includes sun cream, covering up and exposure to the eyes |
| What are the uses of x-rays? What are the dangers of x-rays? | Examine internal structures of body in medical diagnosis and to investigate the crystal structure of materials used in manufacturing. Produced by collapsing starts- used in radio astronomy Cell mutations & cancer- avoid x-rays when pregnant, wear protective clothing and operate x-ray machines remotely |
| What are the uses of gamma rays? What are the dangers of gamma rays? | Treat certain types of cancer, sterilising medical equipment and food products Cause cell mutations and cancers, workers in the nuclear industry wear badges to monitor long term exposure and wither wear dense protective clothing or use remote handling devices |
| What are analogue electrical signals? What are digital electrical signals? | Continuously variable voltages Can have either of only two possible values- represent digits 0 and 1 used I binary number system |
| What are the advantages of digital transmission? | Signals lose energy so signals get weaker and pick up unwanted inference/noise. Amplifies but both wanted signal and unwanted noise are amplifies- reduced analogue quality Digital can be regenerated- amplifying and restoring their distinct 0 or 1 shape Optical fibres allow much wider bandwidth- many different signals can share the same optical fibre- more information can be transmitted along a optical fibre |
| Draw a diagram to show have light rays are reflected from a plane (flat) mirror surface |
Image:
light (image/png)
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| What is the law of reflection? | the angle of incidence= the angle of reflection |
| What is a virtual image? | The image formed in a plane mirror as it appears to be behind the mirror |
| Draw a virtual image. |
Image:
virtual_image (image/jpg)
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| What is the refraction of light? When does it happen? | The bending (changing direction) that happens when light travel from one material to another. Light travels more slowly in substance like glass and water. When traveling into more dense materials it bends towards the normal. |
| What does the degree of bending light depend on? Law of refraction | The refractive index, n, the greater the n that greater the bending effect n= sin i / sin r |
| What is total internal reflection? | When the light ray meets the flat surface at an angle greater than the critical angle it is totally internally reflected. No light emerges form the flat surface of the block because it has all been reflected. |
| What is the critical angle? | The angle at which when a light ray is shone into a material and the light emerges at 90 degrees to the normal. |
| How to calculate the refractive index using the critical angle? | n=1/sin c |
| Draw a diagram when the angle of incidence is: a) 90 degrees b) less than the critical angle c) the critical angle d) greater than the critical angle |
Image:
tir (image/png)
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| Explain the use of total internal reflection (TIR) in optical fibres (OF). | The light goes into the OF and is TIR because the outer layer of a OF has a lower refractive index than its core. The light is TIR all the way to the end. Used for digital communication between computers and for speech and video communication. Used in medicine for 'keyhole' surgery in endoscopes. |
| Draw a diagram of an optical fibre. |
Image:
OF (image/jpg)
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| Sound travels as a .......................... wave through ... . Sound waves cannot travel through a .................. . The range of frequencies a human ear can detect is from ........... to ............ . | longitudinal solids, liquids and gases vacuum 20 Hz to 20 kHz |
| Give an example of sounds waves a) reflecting b) diffracting c) refracting | a) echoes b) sound through open doorways c) stethoscopes |
| What does pitch depend on? What does on oscilloscope do? | How quickly the sound producing system is vibrating microphone converts sound waves into electrical signals. Oscilloscope amplifies these voltages to show how the voltage are changing with time |
| What does the height of the oscilloscope show? How is the pitch show on a oscilloscope? | amplitude- depends on loudness since T=1/f - the time for one complete wave gets shorter as the pitch becomes higher |
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Image:
oscilloscope (image/jpg)
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1. Low quiet sound (same pitch as 2) 2. Low loud sound (same pitch as 1) 3. High loud sound (same volume as 2) |
| What is an addition polymer? | A long-chain molecule that has been formed when many small molecules (monomers) have joined together. |
| Explain the process of making an addition polymer. | Addition polymerisation The monomer molecule contains a carbon-carbon double bond. One of these double bonds in the monomer breaks and this allows the monomer molecules to join together to form a long chain of carbon atoms all bonded together. |
| How do you know that poly(ethane) is an addition polymer? | When it is made , it is the only product made unlike when polymers are made from condensation polymerisation water is also produced. |
| Draw the displayed formula of the polymers: a) poly(ethane) b) poly(chloroethene) c) poly(tetrafluroethene) d) Poly(propene) |
Image:
polymers (image/png)
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| Name some uses for: HDPE (High density Poly (ethane)) MDPE (Medium density poly(ethane)) LDPE (low density poly(ethane)) Why is poly(ethane) used for these things? | HDPE- milk jugs, detergent bottles, margarine tubs, garden furniture MDPE- gas pipes, rubbish bins, storage tanks for fuels LDPE- Plastic bags, cling film Resistant to chemical attack and therefore can be used to store food, drinks and chemicals, including acids an alkalis. |
| What is poly(propene) used for and why? | Food packaging, ropes and carpet Stronger and more hard wearing than poly(ethene) |
| What is poly(chloroethene) used for and why? | Plastic sheets, artificial leather, drainpipes and gutters, insulation for electrical wires and casing for electrical plugs tougher than poly(ethene), very hard wearing and more stable to heat |
| Name 3 ways of disposing of addition polymers. | Landfill- uses up valuable land as they are non-biodegradable (microorganisms can't break them down.) Incineration- Release a lot of heat energy when burnt which can be used to heat homes or generate electricity but carbon dioxide is produced- climate change and toxic gases. Recycling- reduces disposal problems and amount of crude oil used. different polymers must be separated- difficult and expensive |
| What is a condensation reaction? | A reaction in which two molecules react together to form a new, larger molecule with the elimination of a small molecule such as water. |
| What are the two main types of condensation polymers? Give an example of each. | Polyesters e.g. terylene Polyamides e.g. nylon |
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