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  • Created by: devinter
  • Created on: 07-04-16 18:24
How is temperature measured by colour
Termogram
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On a termogram what colours represent hot
white/yellow/red
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On a thermogram what colours represent cold
black/dark blue/purple
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For a warm body what does the rate of cooling depend on
the temperature compared to the surroundings
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Heat travels from the hotter to the ?
colder
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If a object has a high temperature what does this mean?
It is hot
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The hotter an object the ?
higher the temprature
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What is temperature a measurement of?
the average kinetic energy of the particals
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what is energy measured in
Joules (J)
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the amount of energy needed the temperature of the object depends on ?
Mass,the material its made from and the temperature change
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what is specific heat capacity
The energy needed to raise the temperature of 1kg by 1 celcius
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what happens when an object is heated
Its temperature rises and energy is tranfered
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What is specific latent heat
the energy needed to boil or melt 1kg of matirial
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what happens to the temperature when a is boiled or melted
it stays constent
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why does temperature not change during a state of change
the energy is used to break bonds that hold the molecules together
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why is trapped air a good insulator
it stops transferring heat by conduction or convection
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Give examples of trapped air insulation
rock wool loft insulation, double glazing, insulation foam in cavity walls and curtains
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name outer methods apart from air trapping
reflective foil in walls and draght-proofing
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What is conduction
atoms are energized and vibration increases the vibration spreads through the whole matirial
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What is special about conduction in metal
The free electrons transfer kinetic energy and collide with ions as they go the ions vibrate continuously
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What is convection
happens in liquids and gasses and they expand and move faster less dense so rises
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What is radiation
an electromagnetic wave which does not need a medium
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what is a wavelength
he distance between a point on one wave and the same point on the next wave
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what is amplitude
he amplitude of a wave is its maximum disturbance from its undisturbed position.
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What are troughs
The lowest point on a wave
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What are crests
The highest point on a wave
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What is frequency
the number of complete waves per a second
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how fast do electromagnetic waves travel
at the same speed speed (speed of light) in a vacuum and in a strait line through a particular medium
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what does it need to be a refraction
a change in direction due to a change of meduims
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describe what happens at a wave opening
When a wave passes through a gap the diffraction
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electromagnetic waves travel ------- through a particular medium
in straight lines
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when is the refraction greatest
when the width of the gap is about the same size as the wavelength of the wave
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What is the electromagnetic spectrum wave with the shortest frequency
radio waves
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What is the electromagnetic spectrum wave with the shortest wavlenghth
Gamma rays
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what the waves above and below infared radiation
visible and microwaves
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what is a method of communicating by visible light
morse
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what is a method of communicating via radio
radio
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what is a method for communication through microwave
telephone
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what is a method for communication via infared
optical fibers
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in optical fibers where does total internal refection happen
glass-air, water-air and perspex to air boundarys
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advantages of infrared communication
Optical fibres are able to carry more information than an ordinary cable of the same thickness. In addition the signals they carry do not weaken so much over long distances.
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disadvantages of infrared communication
does not transmit through walls, must have direct line of sight and you cannot cover reciver
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advantages of radio communication
they can reach receivers that are not in the line of sight
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disadvantages of radio communication
lots of inferference and limited range
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advantages of using electrical signals to communicate
Relatively cheap and easy. Uses simpler technology than the others.
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disadvantages of using electrical signals to communicate
Requires a wired connection between sender and receiver
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how can light and and Infrared radiation travel along an optical wire
from one end to the other being reflected by the sides of the optical wire
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what happens to light incidence on a boundary when it is above the critical angle
the light cannot pass through the surface - it is all reflected
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what is a digital signal
Digital signals are a series of pulses with two states - on (1)or off(0)
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what is an optical fiber e
a thin rod of high-quality glass
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what is total internal refection
when light is entirely reflected inside a transparent material
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why does the signal in a optical fiber not need to be amplified
he signals in optical fibres do not weaken as much over long distances
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name some ways that you can use total internal reflection in fiber optics
endoscopes and telecommunications (high speed broadband)
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name some of the ways that Lasers can be used
Weapons guidance, laser light shows,cutting materiel in industry and surgery and dental treatment
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what does a laser produce
a beam of light (monochromatic)
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how is information stored on a CD
it is stored in the form of pits and bumps n the bottom surface of the disk
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what does coherent mean
the same frequency and in phase with each other.
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what does low divergence mean
they spread out very little
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how is a CD read
a laser goes one the bumps and bits and gets a digital signal from this
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what are the properties of infarrd radiation
heats the surface of foods reflected by shiny surfaces
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what are the properties of microwave radiation
can cause burns when absorbed by body tissue,penetrates into food,reflected by shiny surfaces and can pass through glass and plastics
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how far does microwave radiation penertrate into food
about 1 cm
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how does infrared radiation cook food
the particles at the top are given kinetic energy then this is transferred through the food via conduction or convection
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how do microwaves cook food
the waves are only absorbed by fat and water in outher layers increasing their kennetic energy
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what signels do mobile phones use
microwave
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what uses different transmission frequencies
radio stations
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what effect does the weather and water have on signal loss
they scatter signel
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what effect doe the curvature of the earth have on signel
loss of line of sight
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when does signal not diffract
when going around a large orbit
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how do you solve the problems of signal loss
limiting the distance between the transmitters and giving them high positioning
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what are the heath risks with mobile phones
Microwaves from the phone can penetrate body tissues to a depth of a few centimetres. They are absorbed, and give up their energy to body tissues. This can cause a small amount of heating
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what do studies show about mobile phones
There have been several studies into the possible health effects of mobile phones and masts. However, there is no conclusive evidence that they can damage your health, or indeed that they cannot
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why may there be danger to residents near a phone mast
Mobile phones communicate with their base stations using low-intensity microwave radiation so may cause harm to there body
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who does the aerial in a Mobil phone cause danger to
the phone user's head
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what increase the danger of mobile phone use
constant use
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what signal connects TVs,automatic doors and DVD players
inferred radiation throughs remote control
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what are short distance data links used for and what signal do they use
computers and mobile phones and infrared radiation
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how do infrared signals carry information to control electrical devices
pressing a button completing the curicut and a coded signal is sent to the LED at the front of the remote control the led sends out pulses which control the devise
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how do thermal imagining cameras work
infrared censors detect body heat
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what is an analogue signel
a signal which have a continual variable value
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why is it easy to remove noise from a digital signal
the digital signel only has two values so interference is easy to read
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how is an analogue wave before its transimtted
it is added to a carrier waveand the combined wave is transmitted
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why is an analogue wave easily get interference
when the wave is amplified so is the interference
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what is Multiplexing
where several digital signals are interleaved or carried together without being mixed
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how do optical fibers use light to transfer data
optical wires allow allow the rapid transmission of data by using light in pulses
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what are the advantages of using optical wires
allows multiplexing and lack of interference in final signal
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what can the for communication do to make it easily accsesable
It can be reflected and refracted
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what type of radiation does wireless technology use for communication
electromagnetic
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why is an arial needed for wireless comunication
to pick up signal
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name some advantages of wireless technology
no direct connection to telephone line, portable and convenient and allows accesses when on the move
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what does long distance communication depend on
it is refracted and the the resulting refection of waves off the ionosphere and then received by the satellite and re transmitted
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what is Refraction and reflection in the ionosphere is similer to
TIR for light(total internal reflection)
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why do radio stations near each outer have very different frequencies
Radio stations with similar transmission frequencies can interfere with each other’s signals
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what are the advantages of DAB broadcasts
more stations available, less interference from other broadcasts
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what are the disadvantages with DAB broadcasts
may give poorer quality and nat all areas are coverd
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what may the diffraction of radiation by a transmission dish effect
the signal resulting in signal loss
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what is detected and recorded by by seismographs
Earthquakes
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what can cause a Tsunami and damage to earth surface
Eartquakes
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what are the two types of wave caused by an earthquake
P and S waves
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what is a P wave
it is a longitudinal wave which travels through both liquids and and solids and travels faster then S waves
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what is special about an S wave
it cannot travel through liquids and is slower then P waves
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name the effects of of exposure to ultra violet radiantion
suntan,sunburn,skin cancer,cataracts and premature skin aging
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why do people use high factor suncream
less damage when higher factors are used and allow longer exposure
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how do darker skins reduce skin cancer risks
they absorb more ultraviolet meaning less ultraviolet reaches underlying skin
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what has decreased the ozone layer
environmental pollution such as CfC's
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why are we at more danger when it comes to ultraviolet light
because of the depleting ozone more radiation reaches earth
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what unexpected discovery was made about the antartic
the reduction in the ozone
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because of the depletion in the ozone what did society do
they stopped using CFC,s and responsibly disposed of them as well as placing a ban in many countries
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Other cards in this set

Card 2

Front

On a termogram what colours represent hot

Back

white/yellow/red

Card 3

Front

On a thermogram what colours represent cold

Back

Preview of the front of card 3

Card 4

Front

For a warm body what does the rate of cooling depend on

Back

Preview of the front of card 4

Card 5

Front

Heat travels from the hotter to the ?

Back

Preview of the front of card 5
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