Flashcards
Physics- P1
Cards in this deck (98)
- 1What is heat?A measure of energy
- 2What is temperature?A measure of hotness
- 3What is the unit of heat energy?The joule
- 4What is temperature measured in?Degrees or Fahrenheit
- 5Where does energy from from and to?From hot objects to cooler ones- eg. Warm radiators heat cold air
- 6What happens to the rate of cooling if there is a greater difference in temperature?It will be faster
- 7What is specific heat capacity?How much energy stuff can store or the amount of energy required to raise the temperature of 1KG of substance by 1 degree Celsius.
- 8What is the specific heat capacity of water?4200 J/KG/degrees
- 9What is the equation for SHC?Energy = Mass x specific heat capacity x temperature change
- 10How can you rearrange the formula for SHC?E= M x SHC x TC
M= E/ SHC x TC
SHC = E/ M x C
TC= E/ M x SHC - 11What is specific latent heat?The energy needed to change state
- 12What is the specific latent heat of melting?The amount if energy needed to melt 1kg of material without changing the temperature
- 13What is the specific latent heat of boiling?The energy needed to boil 1kg of material without changing its temperature
- 14What is the equation for SLH?Energy = mass x specific latent heat
- 15How can you rearrange the formula for SLH?E=M x SLH
M =E/ SLH
SLH= E/ M - 16Why doesn't the temperature rise when melting or boiling?The energy is being used to break intermolecular bonds. These are the flat spots on heating graphs.
- 17Why doesn't the temperature drop when freezing or condensing?Because bonds are forming between particles, which release energy. This means the temperature doesn't go down until all the substance has turned into a liquid or solid.
- 18What is conduction?The process where vibrating particles pass on extra kinetic energy to neighbouring particles
- 19What is convection?It occurs when the more energetic particles move from the hotter region to the cooler region and take ether heat energy with them.
- 20How can you save energy in the home through insulation?Loft insulation, cavity walls and insulation, draught-proofing, thick curtains, double glazing and hot water tank jacket.
- 21What do different colours show on a thermogram?Hot = white, yellow and red
Cold= black, blue and purple
If a house looks 'hot' its loosing heat to the outside - 22What is the equation for efficiency?Useful energy output/
total energy input
x 100 % - 23What is the equation for wave speed (m/s)?Frequency x wavelength
(Hz) x (M) - 24What is the amplitude of a wave?The distance/ displacement form the resting position to the crest
- 25What is the wavelength of a wave?The length of a full cycle of a wave, eg. from crest to crest
- 26What is the frequency of a wave?The number if complete cycles or oscillations passing a certain point per second.
- 27What are the standard units (SI) for wave equations?Metres, seconds, m/s and hertz
- 28How do you convert high frequencies to hertz?1 kHz (kilohertz) = 1000 Hz
1mHz (megahertz) = 1,000,000 Hz - 29What are some wave properties?1) waves travel in a straight line through all substances
2) The direction of travel changes when a wave arrives at an obstacle
3) this can happen by reflection, refraction or diffraction - 30What is reflection?Reflection of light lets us see things
- 31What is the law of reflection?Angle of incidence = angle of reflection
- 32What does total internal reflection depend on?The critical angle
- 33When does total internal reflection occur?When the light travels through a dense substance like glass, water or Perspex, to a less dense substance like air
- 34What is diffraction?Waves spreading out
- 35When do waves diffract?When they pass through a gap or pass an object
- 36What does the amount if diffraction depend on?The size of the gap relative to the wavelength of the wave
- 37What is refraction?Changing the speed of a wave can change its direction
- 38What happens if a light wave hits a boundary between two substances face on?It slows down but carries on in the same direction. It now has a shorter wavelength but the same frequency
- 39What happens if a wave meets a different medium at an angle?Part of the wave hits the denser layer first while another part carries on at the first, faster speed for a while. When the wave has changed direction, it has been refracted.
- 40How many types of electromagnetic wave are there?Seven
- 41What is the electromagnetic spectrum, starting with the smallest wavelength?Gamma, x rays, ultra violet, visible light, infra red, micro waves, radio waves.
- 42What is the mnemonic to remember the electromagnetic spectrum, starting with the smallest wavelength?Good Doctors Understand Very Ill Men Recover
- 43What do the properties of EM waves depend on?Frequency and wavelength
- 44What are the advantages of communicating with light?Advantage: Quick, little interference, multiplexing
- 45What are the advantages and disadvantages of electrical wires and optical fibres?Advantages: can carry lots of information very quickly, secure (harder to tap into when in cable)
Disadvantages: difficult to repair - 46What are the advantages and disadvantages of wireless communication?Advantage: portable (eg. mobiles, laptops)
Disadvantage: relies on an aerial and signal strength often depends on location - 47What is an example of communicating with light?Morse code- each letter of the alphabet is represented by a sequence of 'dots' and 'dashes' which are pulses of light that last for a certain length of time.
- 48What are optical fibres used for?Telephone and broadband internet cables, medical purposes ( to see inside the body without having to operate) and twinkly light such as on artificial Christmas trees.
- 49What is a laser?A narrow, intense beam of monochromatic light
- 50What are the properties of a laser?All waves are the same frequency and wavelength- they are monochromatic.
In phase-the crests/troughs line up.
The waves are coherent (have a fixed phase difference, in this case 0 as they are in phase).
Low divergence- beam is narrow - 51How is infrared radiation used at home?Cooking (grills/toasters), remote controls, TVs, DVD players, computers and security systems (burglar alarms)
- 52How can infrared be used to monitor temperature?Infrared radiation is also known as heat radiation. The hotter the object, the more IR radiation is given out. Infrared can monitor temperature, eg- heat loss through a roof, by using infrared sensors or night vision equipment.
- 53Understand and use the terms source and sink in context of energy lost from housesSources of heat in a
home are radiators,
fires, people and sinks
are places the heat
can escape the home - 54Explain how there will be energy loss in a cavity wall and what further measures could be taken to limit this loss...Conduction through
bricks and then
convection in the cavity
wall, cavity wall insulation
traps bubbles of air
reducing this - 55Describe advantages and disadvantages of DAB broadcastsadvantage they are
quick, disadvantage they
need signal boosting and
some signal can be lost
or interfered with - 56Explain how a laser beam is used in a CD player by reflection from the shiny surfaceinformation is stored on the
bottom surface, information is
stored digitally, information in
the form of patterns of bumps
(known as pits), a CD will
contain billions of pits. - 57Describe why there may or may not be dangers to residents near the site of a mobile phone transmitter mast and to users of mobile phones.Brain could warm if phone
used by younger children
evidence currently not clear.
Same with masts up close
very powerful but as you
move a few meters away this
drops off - 58Explain what long-distance communication depends on?adverse weather and large
areas of surface water scatter
signals, loss of line of sight
due to curvature of the Earth,
no diffraction of microwaves
around large objects,
interference between signals. - 59Describe what happens to light incident on a boundary, eg glass-air, water-air or perspex-air boundary, below, at and above the critical angle.Bends towards normal as
it goes into more dense
medium and away from
normal as it goes into
less dense medium - 60How do IR signals work in a remote control?remotes emit pulses of IR, which act as a digital "on,off" code. The device will detect and decode the pattern of pulses coming from the remote and follow the coded instruction.
- 61What are the disadvantages of IR in remote controls?ypu need to be close to the device you are operating as the beam from a small, low powered remote is fairly small. You also need to point the beam straight at the detector on the device as the IR waves only travel in a straight line.
- 62which waves are used in satellite communication?microwaves
- 63how do satellite TV and phones work?The signal from a transmitter is transmitted into space where it is picked up by the satellite's receiver dish orbiting thousands of kilometers above the earth. The satellite transmits the wave back to earth in a different direction where it is received by a satellite dish on the ground
- 64What are the disadvantages of using microwaves for mobile phones?They have a shorter wavelength so don't diffract much. This means they are affected by the curvature of the earth as they can't bend round it like long-wave radio waves. It also means they're blocked more by large obstacles like hills as they can't bend round them.
- 65What else can affect microwaves in mobile phones?Water- they diffuse in water. In adverse weather, or near a lake, there may be signal loss due to absorption or scattering.
- 66How can you reduce signal loss in microwaves?Position transmitters closer together, in line of sight and high up.
- 67Why may mobile masts be dangerous?The brain could warm if phones are used by younger children. Although the evidence currently not clear, any prolonged exposure (living near masts or excessive use of phone) would increase potential risks.This means we have to balance risks and benefits in terms of location of masts and use of phones.
- 68Why do we use different receivers?To pick up different types of EM waves
- 69What are some examples of receivers?Telescopes, microscopes, satellites
- 70What does the size of the receiver depend on?The minimum size of receiver needed is linked to the size of the wavelength of the wave- the longer the wavelength, the larger the receiver should be.
- 71Which wave needs the biggest receiver?Radio waves, then microwaves, then infrared, then visible etc...
- 72Why do longer wavelengths need bigger receivers?Because of diffraction-when a wave enters a receiver, it passes through a gap. If it diffracts, it spreads out and loses detail. The amount of diffraction depends on the size of the gap compared to the wavelength. The bigger the gap, the less diffraction and clearer information
- 73Which telescopes collect which waves?Optical telescope= visible light
Radio telescope= radio waves - 74How does the size of the telescope affect the detail?The bigger the telescope, the better resolution (more detail) as they cause less diffraction
- 75What is the name for telescopes with small gaps compared to the wavelength they're looking for?diffraction- limited... they have limited resolving power
- 76Why do we settle for a lower resolution with radio waves?because radio waves can be 10,000,000,000 times bigger than light waves and we would need a receiver the size of the UK
- 77How is the problem of low resolution in radio telescopes reduced?radio telescopes are often linked together and their signals combined to get more detailed information- acting like a single giant receiver
- 78How can you collect more EM waves and why is this a benefit?A bigger receiver can collect more EM waves, giving a more intense image- so a bigger telescope can observe fainter objects.
- 79Why are optical microscopes diffraction-limited?they are small as they are usually used to look at things close up- you want to collect light coming from very small areas only. This small gap means you still get some diffraction, making it hard to get a good resolution.
- 80How is information communicated?It needs to be converted into electrical signals before it is transmitted.
- 81How can these signals be sent long distances?down telephone wires or on EM waves
- 82What are the two types of signal?analogue and digital
- 83what is an analogue signal?an analogue signal can take any value within a certain range. The amplitude and frequency of an analogue wave vary continuously.
- 84what is a digital signal?a digital signal can only take 2 values- these tend to be called on/off or 1/0. For example, you can send data along optical fibres as short pulses of light.
- 85Advantages of digital signalsnoise is easier to remove so it remains high quality and you can transmit several signals at once (multiplexing)
- 86How can UV radiation cause skin cancer?spending too much time in the sun increases chances of skin cancer as the suns rays include UV radiation which damages the DNA in your cells.
- 87What other health problems can UV radiation cause?eye problems such as cataracts and premature skin ageing.
- 88why does darker skin give some protection against UV rays?It absorbs more UV radiation. This prevents some of the damaging radiation form reaching more vulnerable tissues deeper in the body.
- 89What does an SPF of 15 mean?You can spend 15 times as long in the sun without burning.
- 90What else can expose us to UV rays?sunbeds
- 91what is ozone?a molecule made up of three oxygen atoms- O3
There's a layer of ozone high up in the earths atmosphere. - 92How does the ozone reduce some UV rays?it absorbs some UV rays from the sun so reduces the amount that reaches the earths surface
- 93Why has the ozone recently got thinner?the use of CFCs- gases which react with ozone molecules and break them up. This depletion of the ozone layer allows more UV rays to reach us on earth
- 94what causes the 'hole' in the ozone over Antarctica?in winter, special weather causes the concentration of the ozone over Antarctica to drop dramatically. In spring it increases again, but the winter concentration has been dropping. The low concentration looks like a 'hole' on satellite images.
- 95What were CFCs used in before the ban?hairsprays and coolants in fridges
- 96Which seismic waves travel through which bits of the earth?P waves travel through
solid and liquid rock (ie
all layers of the Earth), S
waves cannot travel
through liquid rock (ie the
outer core). - 97What are the two types of seismic wave?longitudinal P waves which
travel through both solids and
liquids and travel faster than
S waves. transverse S waves
which travel through solids
but not through liquids and
travel slower than P waves. - 98What are seismic waves recorded with?a seismograph
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- GCSE physics Flashcards on Physics- P1, created by vittoria howard on 17/11/2014.
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- vittoria howard · Nov 2014
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- Apr 6, 2018
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