Paper 4 Higher Flashcards
What is the frequency of wave?
The number of complete cycles of a wave passing a certain point per second (Hz)
What do waves transfer?
Energy, but not matter. If you drop a twig into calm water, the rippled form and move across the surface, without carrying the water or the twig away with them.
How could you generate water waves at a fixed frequency in a ripple tank?
- use a dipper attached to a signal generator
- the signal generator moves up and down at a constant frequency
- which creates waves with the same frequency
How could you find the frequency of a wave in a ripple tank using a cork and a stopwatch?
- float the cork on the water
- start the stopwatch when the cork is at the top of a ‘bob’
- and count how many times the cork bobs with the waves in a set amount of time
- divide the number of bobs by the time to find the frequency
How can you improve the experiment for ripple tank?
Reduce the effect of random errors by repeating the experiments
Refraction
The waves carry on travelling through the new material
Speculation reflection
When waves are reflected in a single direction by a smooth surface
Give an example of an object that showed speculation reflection
A mirror
A torch shines on a piece of paper. Explain why the surface of the paper appears matt, rather than giving a perfect reflection
- paper has a rough surface
- so each incident ray from the torch has a different normal when it hits the paper
- so angle of incidence is different for each light ray as well as angle of reflection
- the light is reflected in all directions (scattered) so you don’t get a clear reflection
What could you use to produce a thin light ray when investigating refraction of light in different materials?
A ray box
A beam of light shone through a rectangular glass block at an angle and comes out the other side. How many times was the light refracted?
Twice- as it entered and left the block
What happens to the frequency of a wave as it enters a new medium?
It does not change
What happens do your ear drum when it is reached by sound waves?
The sound waves cause your ear drum to vibrate
Describe how and why human hearing changes due to ageing?
As a person gets older, the upper frequency limit of what they can hear decreases, and the sound may need to be louder for the person to hear them. This is mainly due to degeneration of the cochlea or the auditory nerve.
Describe why two cup and string phone works?
- when a person speaks into a cup, they generate sound waves
- which causes the air particles in the cup to vibrate
- these vibrating air particles hit the particles of the cup causing them to vibrate
- these particles hit adjacent particles, passing the sound wave through the cup as a series of vibrations
- these vibrations are transferred in the same way through the string to the cup at the other end of the phone
- the vibrating particles of this cup cause the air particles in the cup to vibrate, generating sound waves that the other person can hear
What is ultrasound?
Sound waves with frequencies above 20kHz
Describe what happens when an ultrasound wave meets the boundary between two media
The ultrasound will be partially reflected at the boundary. Some of it will be reflected, and some of it will be transmitted through the boundary
Give one way that ultrasound is used by boats or submarines
To calculate the depth of water or to locate objects deep in the water
Explain how ultrasound waves can be used to produce an image of a foetus in a prenatal scan
- ultrasound waves will reflect off boundaries outside and within the foetus
- how far away that boundary is can be calculated from the speed of the ultrasound and the time taken to reflect and reach each detector using speed = distance/time
- the ultrasound reflections can be processed by a computer to build up an image of the foetus
Rock Music Is Very UnderValued Xylophone Gamma
Radio waves
Microwaves
Infrared waves
UltraViolet
X-rays
Gamma rays
What kind of EM waves can the human eye detect?
Visible light
Describe how the wavelength and frequency of electromagnetic waves change as the spectrum progresses from radio waves through to gamma rays
Wavelength decreases and frequency increases
What are similarities between all electromagnetic waves?
- they’re all transverse
- they travel at the same velocity in a vacuum
- all transfer energy from a source to an absorber
Give one danger associated with exposure to ultra-violet radiation
- damage to cells
- cancer or radiation sickness
- this is because UV radiation is ionising so it can knock of electrons off atoms in the molecules that make up cells
Is exposure to gamma rays more dangerous than exposure to ultraviolet radiation?
Yes
- gamma rays are more dangerous because they have a higher frequency and so they transfer more energy
- this can cause more damage to tissues in the body
- gamma rays can also pass through through the skin and be absorbed by deeper tissues
How does heat link to infrared radiation?
The hotter an object is the more infrared radiation it gives out
EM wave used for cooking and night vision cameras
Infrared
Explain how microwaves can be used to heat up food
- microwaves are absorbed by water molecules in the food
- transferring their energy to the water
- this causes the water to heat up
- water molecules transfer energy to the rest of the molecules in the food by heating
Explain how an antenna converts incoming radio waves into an electrical signal
- when the antenna absorbs the radio wave
- its energy is transferred to the charges within the antenna
- this causes the charged particles to oscillate, forming an alternating current
How are gamma rays used in cancer treatment?
Gamma radiation is targeted at cancer cells to kill them
What kind of images can convex lenses produce?
Real or virtual
Safety features in cars that are designed to increase collision times
- seat belts
- air bags
Speed of sound in the air
340m/s
What is meant by the ‘braking distance’ of a car?
The distance taken to stop once the brakes have been applied
Difference between stopping distance and braking distance
Stopping distance is equal to braking distance plus braking distance
Typical value for human reaction time
0.2-0.8 seconds
How does the rain affect the braking distance of a car?
- it will make the road surface wet
- tyres cant grip the road as well as friction is reduced
- which will increase the distance the vehicle travels before coming to a rest
How to measure a persons reaction time
Ruler drop experiment
- hang a ruler between the persons thumb and forefinger
- drop the ruler without warning and record the measurement at the point where they catch the ruler
- can work out reaction time from the distance the ruler fell
How can a very large deceleration cause a driver to lose control of their vehicle?
They could cause a vehicle to skid. It could also cause the brakes to overheat so that they don’t work as well, which could also cause a loss of control.
Braking distance formula
Braking distance is proportional to speed squared
E.g. if speed increases by 3 times, new braking distance would be 3 squared times old braking distance
Explain why the speed at which a vehicle is travelling affects the breaking force needed to stop it in a certain time.
- greater speed = more energy in the vehicles kinetic energy store
- so more work done to stop it
- as W = f x d, a larger breaking force is needed to do a larger amount of work in the same distance
Typical mass of car
1000kg
What are the main three fossil fuels?
Coal, oil and natural gas
Why does burning fossil fuels contribute to global warming?
Fossil fuels release CO2 when they are burnt. This CO2 contributes to global warming.
Give an advantage and disadvantage of using nuclear power compared to fossil fuels
- nuclear power doesn’t directly emit sulfur dioxide or carbon dioxide, unlike burning fossil fuels
- however, the nuclear waste produced is dangerous and difficult to dispose of
Describe the main energy transfers that take place in a power station that burns fossil fuels
- burning fossil fuels transfers their energy from chemical to thermal energy store of water
- the water boils to form steam which turns a turbine, transferring energy to the kinetic energy store of the turbine
- energy is transferred from the kinetic energy store of the turbine to that of the generator as the turbine turns the generator
- the energy is then transferred electrically away from the power station
State materials that can be used to make biofuels
- farm waste, animal droppings, landfill rubbish
Suggest a renewable energy source that can be used to power a satellite in space
Solar power
Suggest why wind turbines alone may not be able to supply electricity to an area which gets large spikes in the demand for electricity
- wind turbines only work when it’s windy, so they cant always produce electricity
- the power output of wind turbines cant be increased on demand, so they wouldn’t be able to respond to a spike in demand for electricity- a more reliable energy source would be needed
Suggest why biofuels are considered a fairly reliable energy source
- the crops used for biofuels grow fairly quickly and can be stock piled for when they are needed
- this means they provide a reliable energy source as there’s always reserves of biofuels to burn
- so electricity can be produced even if there’s an increase in demand
Compare the reliability of tidal and solar power
- both are fairly reliable
- solar power can generate electricity even when its cloudy
- tidal power relies on the tides, which always occur twice daily
- the output from both sources will vary due to amount of sunlight or tidal height
- output cannot be increased on demand, which makes both sources less reliable
Why has electricity use in the UK decreased this century?
Appliances are becoming increasingly efficient and people are becoming more careful with energy use in their homes
How does the potential difference across the secondary coil compare to that across the primary coil in a step up transformer?
P.d across the secondary coil is greater than the potential difference across the primary coil
What are transformers used for in the National grid?
Step up transformers- to increase the p.d of the electricity supply before it is transmitted across the country via the national grid
When electricity supply reaches consumers, a step down transformer is used to bring the p.d down
What is the purpose of an earth wire in an appliance?
For safety- it is attached to the metal casing of an appliance so the current flows through it if the live wire ends up touching the casing
Functions of live wire and neutral wire in an electrical appliance
Live wire- carries the alternating voltage
Neutral wire- completes the circuit to allow current to flow in the appliance
Time taken for geostationary vs polar satellites orbit
Satellites in geostationary orbits take 24 hours
Satellites in polar orbit take less than 2 hours
All planets with increasing distance from sun
Mercury, Venus, earth, mars, Jupiter, Saturn, Uranus and Neptune
Similarity and difference between natural and artificial satellites
- natural satellites occur naturally e.g the moon whereas artificial satellites are man-made
- both orbit planets
Body R is at a higher temperature than body S
What does this mean about its radiation
Body R emits radiation with a mean higher frequency
What do we know about distant galaxies?
- they show more red shift
- the distant galaxies are moving faster apart than nearby ones
What half life and radiation is best to use as a medical tracer?
- half life 6 hours
- gamma radiation
Infrared energy transfer example
From heating element of a toaster to the bread inside
What happens to a sound when it is travelling in air and it enters the water?
- speed increases
- frequency stays the same
- wavelength increases
Factors which could increase thinking distance
- influence of alcohol
- drugs
- old age
Stopping distance=
Thinking distance + braking distance
What is the cosmic microwave background radiation?
The low frequency microwave radiation that scientists have detected coming from all directions and all parts of the universe
What is red shift and what is it caused by?
An increase in the wavelength of light coming from an object, caused by that object moving away from the observer
List each stage in the life cycle as a star the same size as the sun
Cloud of dust and gas, protostar, main sequence star, red giant, white dwarf and planetary nebula
Process that forms helium nuclei from hydrogen nuclei in main sequence stars
Nuclear fission
Describe how a white dwarf is produced from a red giant
When a red giant becomes unstable and ejects its outer layers of dust and gas as a planetary nebula, it leaves behind a hot, dense solid core- a white dwarf
Two possible results of a supernova
Neutron star or black hole
- most massive stars form black holes
Stars are formed from dust and gas.
What causes the dust and gas to undergo fission?
- gravity
- very high temperatures or pressures
Describe the difference between nuclear fusion and nuclear fission?
- in fusion nuclei join but in fission they split
-fusion occurs at a higher temperature than fission - more energy released in fusion
Advantage of using nuclear power to produce electricity
- no co2 produced so does not contribute to global warming
- fuel readily available
Disadvantage of using nuclear power to produce electricity
- radioactive waste produced
- expensive to build
- non renewable
Explain how braking stops a car in terms of energy stores
- store of KE in moving car
- transferred thermally to thermal energy store in brakes
Alpha particle
2 neutrons 2 protons (helium nucleus)
Beta particle
An electron
Why do some atomic nuclei undergo radioactive decay?
To become more stable
P waves
Longitudinal
What type of nuclear radiation can pass through a sheet of paper or a thin aluminium sheet, but not a thick sheet of lead?
Gamma radiation
What is alpha blocked by?
Paper
What is beta blocked by
Aluminium
What type of radiation is emitted by isotopes used as medical tracers?
Gamma radiation
