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What piece of equipment shows temperature?
Thermogram
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What is temprature a measuremnt of?
Hotness on a arbitrary scale
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What happens to the kinetic energy when the temperature is increased?
It increases
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What is heat a measurement of?
Internal energy measured on an absolute scale
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What is specific heat capacity?
The energy needed to raise the temeprature of 1kg by 1 degree
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What is specific latent heat?
The energy needed to melt or boil 1kg of a material
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What is specific latent heat and specific heat capacity measured in?
Specific latent heat=joule per kilogram, specific heat capacity=joules per kilogram degree Celsius
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What happens when an object is heated?
The temperature increase and energy is transferred
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What happens when an object is heated meaning it changes state?
Energy is transferred but the temperature remains constant
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What happens when a substance changes state?
Energy is needed to break the bonds that holds the bond together meaning the temperature doesn't change when this is taking place
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Double glazing reduces heat loss through conduction, how?
The gap between the glass is filled with a gas or vacuum(the particles in a gas are far apart), this makes it very difficult to transfer energy. In a vacuum there are no particles so energy cannot be transferred
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How does loft insulation reduce heat loss by conduction and convection?
Warm air in the houses rises so reaches the ceiling, the top of the ceiling warms the air in the loft, this air is trapped by the loft insulation. Both sides of the ceiling are the same temperature so no energy is transferred.
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What happens if there is no loft insulation?
The warm air in the loft can move by convection and heat the roof tiles, heat is transferred to the outside through conduction
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How does cavity wall insulation reduce energy loss through conduction and convection?
The air in the foam is a good insulator, the air cannot move through convection because it is trapped in the foam
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The new insulation blocks have shiny foil on both sides how does this reduce energy by what?
Radiation, energy from the sun is reflected back to keep the house cool in summer, in the winter energy is reflected back into the home
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What is conduction?
The transfer of kinetic energy between particles
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What is convection?
A gas expands when it's heated, this makes it less dense so it rises
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What is radiation?
Its from the sun and does not need a material to transfer energy, it can transfer energy through a vacuum
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What shows energy transformations?
Sankey diagrams
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What's the formula for payback time?
cost of insulation/annual saving
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What's amplitude?
The maximum displacement of a particle from it's rest position
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What's frequency?
The number of waves that pass a point in 1 second
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What's the wavelength?
The distance between two succesive points on a wave having the same displacement and moving in the same direction
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How do you calculate wave speed?
frequency x wavelength
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What's the order of the electromagnetic spectrum?
radio,microwave,in fared, visible, ultraviolet, x ray, gamma
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Why does refraction occur?
because the speed of the wave decrease as it enters a more dense medium and increases as the wave travels from a more dense to a less dense medium
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How does refraction effect the frequency and wavelength?
The frequency stays the same, wavelength changes
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What is diffraction?
The spreading out of waves as they pass through a gap
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When does most diffraction occur?
When the gap is the same size as the wavelength
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Do larger gaps shows more or less diffraction
less
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What's morse code ans what's it an example of?
Morse code is used for communication, it uses dashes and dots to represents letters, its an example of a digital signal
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What is white light made up of?
Different colours of different frequencies out of phase
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What's laser light?
It has a single frequency, in phase and shows low divergence
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How is laser light used to read CD's?
The surface of the CD is pitted, the pits represent the digital signal, the laser is shone onto the CD and the difference in reflection due to the pits provides the information
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What happens to the angle of refraction when light passes from a more dense medium to a less?
It's larger than the angle of incidence
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When the angles of refraction is 90 degrees what happens?
The angle of incidence is called the critical angle
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What happens when the angle of incedence is bigger than the critical angle?
Total internal reflection
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Describe endoscopy?
Light passes along optical fibres to illuminate inside the body, the light us reflected, the light passes back up another set of fibres to an eyepiece or camera
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How well do infared waves penetrate foods compared to microwaves?
Infared do not penetrate easily, microwaves penetrate up to 1 cm of food
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Why is the door on a microwave shiny?
Microwaves penetrate glass or plastic but reflect of shiny surfaces reducing the energy lost.
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What porperties does a wave need to transfer the most energy?
High frequency, short wavelength
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How does infared radiation cook food?
Particles on the surface absorb energy, kinetic energy increases, rest of food cooked through conduction
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How do microwaves cook food?
Water or fat molecules in the food vibrate,kinetic energy increases, energy is transferred by conduction
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What is needed for microwave communication?
A transmitter and receiver that must be in line of sight
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How are satellites used in microwave communication?
The signal from earth is received, amplified and re-transmitted back to earth
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Why are satellites used?
They are in line of sight because there are no obstructions in space, large aerials can handle lots of phone calls at once
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What can effect signal strength of mobile phones?
Adverse weather and large areas of water can scatter signals, microwaves don't show much diffraction, the curvature of the earth limits line of sight so transmitters have to be on high buildings
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What's a microwaves wavelength?
1mm to 30cm
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How are digital signals used in TV remotes?
Pressing a button on the remote completes a circuit, a coded signal is sent to the light emitting diode(LED).The LED transmits a series of pulses, this is received by a devise in TV that decodes the signals
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What are the advantages of TV's and radios being digital not analogue?
Improved signal quality for picture and sound, a greater choice of programmes, information services, a choice to interact with prgrammes
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What happens before an analogue signal is transmitted?
Its added to a carrier wave
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Describe the carrier wave?
It's frequency is normally higher, interference from another wave can be added to the carrier wave and transmitted
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if the wave is amplified what happens to the interference?
Amplified also
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What are the advantages of digital signals?
Multiplexing which allows a large number of digital signals to be transmitted at once, interference is not apparent
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What happens to radio waves in the earths atmosphere?
They are reflected and refracted
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How does frequency effect refraction?
Less refraction at higher frequencies
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Radio station normally have their own frequency, what factor means radio stations can have the same frequency?
If the two stations are further enough away for the frequencies not to interfer
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What factor can affect interference?
In unusual weather conditions the waves can travel further and might interfere
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What does DAB stand for and what does it do?
Digital audio broadcasting, it eliminates interference between other radio stations
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How do radio waves act in the ionosphere?
They reflect off it, they behave like an optical fibre(total internal reflection)
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What reflects radio waves?
Water but not land
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Why is is useful that radio waves reflect of the ionosphere?
They don't need to be received by an aerial that's not in line of sight
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Do microwaves pass through the ionosphere?
Yes
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What are some communication problems?
Radio waves are diffracted when they meet an obstruction, signals may be refracted in the atmosphere, transmitted beam is slightly divergent, some energy is lost from the transmitting aerial due to diffraction
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What type of equipment shows earthquake waves?
Seismograph
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What do L waves do?
Travel slowly around the surface
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Describe P waves?
Longitudinal pressure waves, travel between 5km/s and 8km/s,
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Describe S waves?
Transverse waves, travel between 3 km/s and 5.5 km/s
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What can P waves travel through?
Solids and liquids
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What can S waves travel through?
Solids
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How do scientists know the core is liquid?
S waves will not travel through liquids and aren't detected on the opposite side of earth to an earthquake
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How can scientists work out the size of the earth core?
Because P waves are refracted by the core, the paths the wave take can work out the size
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What pigment produces and tan?
Melanin
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Why do people with darker skin not tan easily?
Because the UV radiation is filtered out
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What's the formula to work out maximum time to spend in the sun?
published normal burn time x SPF
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Where is the ozone found?
In the stratosphere
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What does the ozone layer do?
Filter out UV
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What has cause a hole in the ozone layer?
CFC's from aerosols and fridges
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Where is the ozone thinnest ans why?
The South pole because the CFC chemicals work best in cold conditions
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What has been done to stop the depletion of the ozone layer?
An international agreement to reduce CFC's
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How do scientists monitor the thickness of the ozone layer?
Satellites
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Other cards in this set

Card 2

Front

What is temprature a measuremnt of?

Back

Hotness on a arbitrary scale

Card 3

Front

What happens to the kinetic energy when the temperature is increased?

Back

Preview of the front of card 3

Card 4

Front

What is heat a measurement of?

Back

Preview of the front of card 4

Card 5

Front

What is specific heat capacity?

Back

Preview of the front of card 5
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