Physics P1 Flashcards
Heliocentric model
Sun in the centre with everything orbiting it with the moon orbiting earth
Geocentric model
Earth is in the centre and everything orbits it, moving in its own little circle
Interface
Boundary between two materials
An image from a converging lense
Upside down, a real image
Real image
An image where the rays of light actually meet at the point where the image is seen
Virtual image
The rays of light appear to come from an image but actually don’t. A virtual image cannot be shown on a screen
Image from a reflecting telescope
Right way round, sharper, virtual image
Frequency
The number of waves passing a point each second
Measured in hertz (Hz)
Wavelength
The distance from a point on one wave from the same point on the next wave. Measured in metres
Amplitude
The maximum distance of a point on the wave from its rest position. Measured in metres.
Wave speed equation
Wave speed (metres/second) =
Distance (metres)
————- = —————-
Time (seconds)
Wave speed
frequency x wavelength
Hz x m
Electromagnetic spectrum
Radio waves, microwaves, infrared, visible light, UV, X-rays, gamma rays
Shortest wavelength, highest frequency, most dangerous
Uses of electromagnetic radiation
UV- Shine it on banknotes
Radio waves- broadcast and communication
Infrared- CCTV camera , remotes, toasters,optical fibres
Microwaves- mobile phone signals
Gamma rays- detect and kill cancer, sterilise medical equipment
Ionising radiation
Radiation that removes electrons from atoms to form ions, these can mutate and cause cancer
Parts of the electromagnetic spectrum telescopes can detect
Visible light, X-rays, ultraviolet, radio waves
Life cycle of star
Cloud of gas (nebula), protostar, average star,
- red giant, shell of gas, white dwarf, black dwarf.
- red supergiant, supernova, neutron star or black hole
Big Bang theory
The whole universe and everything in it started out as a tiny piece of matter around 13.5 billion years ago. The universe expanded and is still expanding. Nothing is being created, and everything is moving away from each other.
Steady state theory
The universe has always existed and is expanding, new matter is being created to fill the spaces.
Red shift
When the wavelengths from far off stars and galaxies is longer than expected
Infrasound
Sound with frequencies below 20 Hz
Elephants and whales use it to communicate
Can be used to detect earthquakes an meteors
Ultrasound
Sound with a frequency above 20 000 Hz
Dolphins use it to communicate
Bats use it to detect their surroundings
Boats use it to detect how deep the water is
Can be used to make images of things inside the body
Seismic waves
Movements inside the earth, such as earthquakes,which cause waves to be transmitted through the earth.
Seismometers
Instruments that detect seismic waves
Focus
The place inside the earth where the rock suddenly moves or fractures
Epicentre
The point on the surface directly above the focus
P waves
Primary waves
Longitudinal waves
Faster than S waves
S waves
Secondary waves
Transverse waves
Slower than P waves
Renewable resources
Resources that will not run out
- solar energy
- hydroelectricity
- wind turbines
- geothermal energy
- tidal power
- wind power
Non renewable resources
They will run out, they are not sustainable and produce waste gases
- coal
- oil
- gas
- nuclear fuel
Step down transformer
Lowers the voltage increases the current
More turns on primary coil
The potential difference produced by a transformer can be calculated by………………………………..
Voltage (primary) = Turns (p.)
------------- -------------
Voltage (secondary) Turns (s.)
Power formula
Power = Energy used
——————
Time
Watt, W = Joule, J
————
Seconds, S
Other formula for power
Power = Current x Voltage
watt,W= amps,A x volt,V
Cost formula
Cost = power x time x cost of 1kWh
p = kW x hours x cost
Payback time
Cost
——————–
Savings per year
Energy conversion diagram / sankey diagram
Shows the amount of energy converted or transferred
Efficiency
How good a device is at converting energy into useful forms
Efficiency formula
Efficiency=
Useful energy transferred by device
————————————————
Total energy supplied to device
x 100
Transformer
Electricity is generated and transmitted around the country by a system if cables and wires called the national grid. It starts at a power station where a step up transformer increases the voltage because if the voltage increases the current is reduced so the wire does not heat up, once through the transmission lines, transformers decrease the voltage for factories then the last step is when in local substations the voltage is decreased to it can get to homes and shops safely.
All waves have…
Wavelength
Frequency
Amplitude
Speed
Wavelength
Distance from one peak to the next
Waves transfer..
Energy and information without transferring matter
Transverse
The vibrations are at 90 degrees to the direction of travel of the wave
S waves
Most waves are transverse, ripples on water
Longitudinal
The vibrations are along the SAME DIRECTION as the wave is travelling
Sound and ultrasound
P waves
Oscilloscopes
Show things as transverse waves
Reflection
When a wave hits a boundary between one medium and another some of its energy is reflected
Something reflects because of a change of density
Angle of reflection equals…
Equals angle of incidence
Waves travel at different speeds in substances which have different densities
EM waves travel more slowly in denser media
Sound waves travel faster in denser substances
When a wave crosses a boundary between two substances
It changes speed
If the wave hits the boundary face on
It slows down but carries on in the same direction
If a wave meets a different medium at an angle
One part of the wave hits the denser layer first and slows down
While the other part carries on at the first, faster speed so the wave changes direction
Converging lense
-Convex lens-bulges outwards
-Causes parallel Rays of light to converge to a focus
-
Axis is a line passing through the middle
-
Focal point
Where all the Rays hitting the lens parallel to the axis meet
Each lens has one in front of the lens and behind
Refracting telescope
Uses two converging lenses
Objective lens and eyepiece lens
Virtual Image
Hydroelectricity
- Uses a dam
- Rainwater is caught and allowed out through turbines
- Immediate response to demand
- Initial high costs but minimal running costs and reliable
Wave Power
- Provides up and down motion for turbine
- Fairly unreliable
- Uses waves close to shore which are less powerful than waves out at sea
Tidal barrages
- Big dams across river estuaries with turbines in them
- Tide comes in and fills up estuary, water allowed out through turbines at controlled speed
- Can only be used in a few suitable estuaries but reliable
Wind power
- Each wind turbine has its own generator inside
- No pollution
- Spoil view and noisy
- Only work when it’s windy
Solar cells
- Generate electricity on a small scale
- In sunny countries it’s very reliable
- Only in daytime
- Cost effective
Geothermal energy
- Only possible in places where hot rocks are near the surface
- Water is piped down and the steam is used
- No real environmental problems
- High set up costs
Biomass
- Anything from farm waste, Animal droppings, landfill rubbish
- Burnt to drive turbines or fermented to produce ‘biogas’
- Carbon neutral
Less dense to dense
Towards the normal
Dense to less dense
Away from the normal
At 2F the image is
Same size
Real
Upside down
Between 2F and F the image is
Bigger
Real
Upside down
Between F and lens the image is
Bigger
Virtual
Upright
How does a refracting telescope work
Objective lens converges the Rays to form a real image at the focal point
The Rays of light from the image enter the eyepiece lens and it spreads them out so they fill more of your retina and make the image look bigger
SETI
Looks for radio signals from other planets
Nebula to main sequence star
The force of gravity makes the gas and dust spiral in together
Gravitational energy is converted to heat energy so the heat rises
Main sequence star
When the temperature gets high enough, hydrogen nuclei undergo thermonuclear fusion to form helium nuclei and give out massive amounts of energy
Long stable period, heat created by fusion provides an outward pressure to balance the force of gravity pulling inwards
Main sequence to red giant
Hydrogen in the core begins to run out and the star swells into a red giant (red because the surface cools)
Red giant to planetary nebula to white dwarf
Becomes unstable and then ejects its outer layer of dust and gas as a planetary nebula
This leaves behind a jot dense solid core which cools down and eventually disappears
Red supergiant to supernova
Start to glow more brightly again as they undergo more fusion and expand and contract several times forming heavier elements I’m various nuclear reactions
Eventually they explode in a supernova
Supernova to neutron star or black hole
Exploding super nova throws put the outer layers of dust and gas into space leaving a very dense core called a neutron star
If is big enough it will become a black hole
How was infrared discovered by Herschel
Shone white light through a prism to create a spectrum on a screen
He used a thermometer to measure each colours temperature- it increased from violet to red
Just past red was the hottest
How did Ritter discover ultraviolet
Silver chloride turns white to black when exposed to light so he measured how fast silver chloride coated strips changes when exposed to different colours
In a dark room he created a spectrum using a light source and a prism and exposed the strips to each colour
Was quicker near the blue end of the spectrum and quickest just after violet
Dangers of EM
Microwaves-heat human body cells Infrared- skin burns Ultraviolet-Skin cancer, eye damage X-Rays- cancer Gamma rays- cancer, cell damage
Alpha
Helium nuclei
Beta
Electrons
Gamma rays
Electromagnetic radiation
Spectrometers
Telescope directs beam of light at a slit
This diffracts the light and splits it into a spectrum
The light spectra from stars and galaxies contain dark lines from light being absorbed by elements in a stars atmosphere
Can be used to work out what stars and galaxies are made of
Elements and spectrometry
Each element has its own absorption spectrum
Tectonic plates
They are like rafts that ‘float’ on the mantle
Convection currents cause them to drift
Why do seismic waves refract
The density of the mantle and core change which is why there’s a curved path
What direction do electrons flow in
Positive to negative
Anticlockwise
How do u induce a voltage
Moving a magnet through a coil
Electromagnetic induction
If a magnet is moved the opposite direction in the cool
Current is induced in the opposite direction
If the magnet is moved the same way with the opposite side
Current is induced in the opposite direction
What effects the size of an induced current and voltage
Strength of magnet
Area of coil
Number of turns on coil
Speed of movement- higher frequency
Environmental problems with non renewable
- Fossil fuels release CO2
- Burning coal and oil releases SO4
- Coal mining makes a mess of the landscape
- Oil spillages cause environmental problems
- Nuclear waste is dangerous and difficult to dispose of
- Cost of Nuclear is high
- Nuclear catastrophes
Setting up power stations considerations to take
- Set up costs
- Set up time
- Running/fuel costs
- Reliability
- Environmental issues
- Location issues
How do solar panels use heat radiation
Water pipes under a Matt black surface and shiny inner surface
How do survival blankets use heat radiation
Silver blankets stop body heat radiating away
Types of energy saving stuff
- Loft insulation
- Hot water tank jacket
- Double glazing
- Draught proofing
- Cavity Walls and insulation
- Thick curtains
People with transmitting huge amounts of energy
- Still isn’t very efficient, power losses high
- High voltage is a risk to people
- People worried about long term effects of living near power lines
Step up transformer
Voltage increase current decrease
More turns on secondary coil
