Paper 1 Overview Flashcards
SP1a - What is a scalar quantity?
A quantity with a magnitude (size) but no direction
SP1a - What is a vecotr quantity?
A quantity with a magnitude (size) and direction.
SP1a - What are the six main vector quantities?
- Velocity
- Displacement
- Acceleration
- Force
- Weight
- Momentum
SP1b - How do you work out average speed?
Speed (m/s) = Distance(m) / Time(s)
SP1b - What is the average speed of walking and cycling?
- Walking: 1.4m/s
- Cycling: 6m/s
SP1b - What are the two things you can use to measure speed in an experiment?
- Stopwatch
- Light gates
SP1b - On a distance/time graph, what does the gradient represent?
The velocity
SP1b - On a distance/time graph, what does a horizontal line represent?
The object is stationary
SP1b - On a distance/time graph, what does a curve represent?
The object is accelerating/deccelerating
SP1c - How do you calculate acceleration?
Acceleration (m/s²)
=
Change in velocity (m/s) ÷ Time (s)
SP1c - What is the value of acceleration due to gravity?
9.8m/s² (rounded to 10m/s²)
SP1d - What does a straight slope mean on a velocity time graph?
Acceleration
SP1d - What does a horizontal line mean on a velocity time graph?
The object is moving at a constant velocity
SP1d - What does a curve mean on a velocity time graph?
Changing acceleration
SP1d - What does the area under a velocity time graph represent?
The distance covered
SP2a - If a rocket experiences 800kN of thrust upwards and its weight is 300kN, what is the resultant force?
800 is up 300 is down.
800 - 300 = 500
500kN upwards
SP2b - What is Newton’s first law?
- A moving object will remain at a constant velocity until an external force acts on it.
- A stationary object will remain stationary until n external force acts on it.
SP2b - What is centripetal force?
- An object moving in a circle at a constant speed is contantly changing velocity and so is constantly accelerating towards the centre of the circle.
- As the car is accelerating, there must be a force acting on it.
- This is centriputal force and always acts towards the centre of the circular motion.
SP2b - What three things can provide centriputal force?
- Tension
- Friction
- Gravity
SP2b - How can the amount of centripetal force needed for an object to remain in circular motion be altered?
The amount of force needed increases if you:
- Increase the mass of the object
- Increase the speed of the object
- Decrease the radius of the circle
SP2c - What is the difference between weight and mass?
Mass is the quantity of matter in an object and weight is the pull force the object experience depending on the gravitational field strength.
Weight - N
Mass - Kg
SP2c - What formula links weight and mass?
w = m x g
(Weight = mass x gravitational field strength)
SP2c - Describe the forces acting on a skydiver as they jump out of a plane?
- As soon as they jump out, the only force acting on them is their weight and so they accelerate downwards
- Air resistance increases with speed and so as they accelerate, it increases until eventually it is equal to their weight
- At this point the resultant force acting on the skydiver is 0 and so they stop changing velocity as they have reached terminal velocity
- Once the parachute is launched, the air resistance greatly increases causing a decceleration
- As the velocity decreases so does the air resistance until it is again equal to the weight
- It now reaches a new lower terminal velocity
SP2d - What is Newton’s second law of motion?
The acceleration of an object depends on:
- Its mass
- The Force acting on it
SP2d - What equation uses Newton’s second law?
F = m x a
(Force = mass x acceleration)
SP2d - What is inertial mass?
- A measure of how difficult it is to accelerate an object.
- The ratio of the force needed to accelerate an object over the acceleration produced.
- If an object has a lerger inertial mass, it will require more force to produce a given acceleration than an object with a larger inertial mass.
SP2d CP - How can you investigate the acceleration of a trolley using light gates?
- Attach masses to the end of the trolley hanging off the end of the table over the ramp and the pulley .
- Set up two light gatesa measured distance apart.
- Connect the light gates to a data logger.
- Release that masses. using your data log information, divide the length of the card by the time the light gate was active for each of the light gates.
- Divide the difference between these two velocities by the time between each of them to get the acceleration.
- To investigate how mass affects this, repeat with different masses.
SP2e - What is Newtons third law?
When objects interact the forces exerted are equal and opposite.
SP2e - When a person is standing, describe the action-reaction forces.
The downward force of weight from the person on the ground and the upward reaction force of the ground on the person.
SP2e - What is the difference between balanced forces and action-reaction forces?
Balanced forces all act on the same object, action-reaction forces act on different objects.
SP2f - What is the formula for momentum?
p = m x v
(momentum [kg m/s] = mass x velocity)
SP2f - What equation connects force and momentum, and how can this be derived?
F = Δp / t
(Force = change in momentum ÷ time)
As F = m x a
and a = Δv / t
we can see that
F = (m x Δv) ÷ t
Since m x v = p
then m x Δv = Δp
So, F = Δp ÷ t
SP2f - What is the law of the conservation of momentum, and how id this affected by the fact that momentum is a vector quantity?
- Total momentum before = total momentum after
- Since momentum is vector, an object moving in the opposite direction has a negative momentum and this must be taken into account when calculating momentum.
SP2g - What is stopping distance?
- The total distance it takes for a car to stop once the driver reacts to an external stimuli.
- This consists of: Thinking distance & braking distance
SP2g - What is the average reaction time to visual stimuli and what can affect this?
- 0.25 seconds.
- This can be longer if the driver has taken drugs/ alcohol or hasn’t had enough sleep
SP2g - What can increase the braking distance of a car?
- Increasing its momentum:
- If it is moving faster
- Higher mass
- Reducing friction:
- Brakes are worn
- Rain/ice/snow on the roads
- Loose gravel
SP2h - How can you combine the formulae for work done and KE to have a formula for braking distance?
E = F x d
KE = 1/2 x m x v²
(1/2 x m x v²) ÷ F = d
d = (m x v2) ÷ 2F
Mass x velocity² divded by 2 force = braking distance
[Also can be (p x v) ÷ 2F = d Momentum x velocity ÷ 2 Force = Braking distance]
SP2i - What are the four main safety features of a car?
- Air bags
- Crumple zones and side impact bars (Easily give way causing themsleves to crush)
- Seat belts
SP2i - Explain how the safety features of a car link to the equation linking force and momentum.
- F = Δp / t
- All the safety features of a car absorbe kinetic energy, increasing the time taken for the momentum to reduce.
- As the time is increased, the force is reduced.
SP3a - What are the 9 energy stores?
- Kinetic
- Thermal
- Gravitational Potential
- Elastic Potential
- Sound
- Light
- Chemical
- Nuclear
- Electrical
SP3a - By what processes can energy be transferred?
- Heating
- Forces
- Electricity
SP3a - What is the law of the conservation of energy?
- Energy cannot be created or destroyed, only transferred between stores.
- In a closed system, the total start energy = the total end energy
SP3a - What is unit for measuring energy?
Joules (J)
SP3a - What diagram might you use to display the transfer of energy?
A sankey diagram, The width of the bars represent the amount of energy.
SP3b - What is it called when energy transfers to its surroundings by heating?
Dissipation
SP3b - What might you do to moving parts to reduce enrgy loss and why?
- Use a lubricant.
- Moving parts cause friction which causes enrgy to dissipate losing energy.
- Lubrication reduces friction and thus energy loss by friction.
SP3b - What is the most common form of wasted energy?
Thermal
SP3b - How do you calculate efficiency?
total useful energy output / Total energy input
Efficiency is on a scale of 0 to 1. To calculate it s a percentage, x100
SP3b - How do you distiguish useful and wasted energy on a sankey diagram?
The useful energy has an arrow going staright while the wasted energy arrow turns off.
SP3c - How is a convection current formed?
Part of a fluid (Liquid/gas) that is warmer than the rest rises up once it reaches the top it looses thermale enrgy and sinks back down. This forms a current.
SP3c - Why do cavities in walls help insulate a house?
- When thermal energy wants to travel it requires particles to travel throgh.
- It gives energy to these particles which causes heat.
- A cavity in the wall means that there is air in which particles will collide less and heat will pass through less, so heat can’t escape as easily.
SP3c - How is a flask able to maintain the temperature of its contents?
- Silver coating on the outside and inside reflects radiation which would transfer thermal energy
- Glass walls with vacuums between create a cavity stopping heat from entering or escaping
- Plastic stopper stops heat from escaping
SP3d - What is the formula for change in gravitational potential energy.
ΔGPE = m x Δh x g
(change in GPE is mass x change in height x gravitational field strength)
SP3d - What is the gravitational field strength on earth?
9.81 (Can be rounded to 10) m/s² or N/Kg
SP3d - What is the formula for Kinetic energy?
KE = ½ x m x v²
(Kinetic energy = mass x velocity² divided by 2)
SP3d - As an object falls describe the change in energy stores in terms of GPE and KE.
- As an object looses height, it looses GPE this ‘lost’ energy transfers, mostly, into kinetic energy as it is moving.
- Some other energy may transfer into sound energy
SP3e - What are the four main types of non-renewable energy sources?
- Fossil fuels:
- Natural gas
- Coal
- Oil
- Nuclear
SP3e - Apart from the lack of sustainability, why is burning fossil fuels not beneficial?
It releases Carbon dioxide and other gases that are harmful for the environment as they contribute to climate change.
SP3f - What are the pros and cons of using solar panels and solar energy?
Pros:
- Will never run out
- Won’t release carbon dioxide once installed
Cons:
- Energy output depends on sun and so may not always be available
SP3f - What are the pros and cons of using wind turbines?
Pros:
- Will never run out
- Won’t release carbon dioxide once installed
Cons:
- Many have to be installed and they have low output
- Takes up large spaces and soem say this spoils the view
- Not reliable
SP3f - What are the pros and cons of hydroelectric energy?
Pros:
- Very reliable
- Will never run out
- Won’t release carbon dioxide once installed
Cons:
- Habitats destroyed
- Only useful when water sources are nearby
SP3f - What are the pros and cons of Tidal energy?
Pros:
- Extremely reliable
- Will never run out
- Won’t release carbon dioxide once installed
Cons:
- Some argue that it harms wildlife
SP3f - What are the pros and cons of wave energy?
Pros:
- Reliable
- Will never run out
- Won’t release carbon dioxide once installed
Cons:
- Small scale and experimental
- Low output
SP3f - What are the pros and cons of geothermal energy?
Pros:
- Will never run out
- Won’t release carbon dioxide once installed
- Extremely reliable
Cons:
- Only useful near volcanic sites
SP3f - What are the pros and cons of biofuel?
Pros:
- Will never run out
- Carbon neutral (Burning fuels releases carbon put planting plants took in carbon so its neutral)
- Useful as they can power vehicles
Cons:
- Can take up space that could be used for food, this can increase the price of food.
SP4a - Describe a transverse wave, giving examples.
- Paritcles vibrate perpendicular to their direction of travel.
- They transfer energy
- They all travel at the same speed in a vacuum (3x108)
- All EM waves are examples of this
- Water waves are transverse
SP4a - Describe a longitudinal wave, giving examples.
- Particles vibrate parallel to direction of travel
- Areas of compression and rarefraction
- Sound waves
- Seismic P waves
SP4a - Descirbe the following features of a transverse wave:
- Frequency
- Period
- Wavelength
- Amplitude
- The amount of waves passing in a second (measured in Hertz Hz. Determines pitch or colour)
- The time it takes one wave to pass a point
- The length in m from one point to the next identical point of a wave
- The distance in m from a waves rest position to its trough or peak
SP4b - What are the two formulas for wave speed?
v = d/t
(Velocity = distance ÷ time)
v = f x λ
(Velocity = frequncy x wavelength)
SP4b - Using two buoys, how can you measure the speed of waves?
- Measure the distance the buoys are apart.
- Record the amount of time it takes for a single wave to get from one to the other.
- Do distance/time to get the wave speed.
SP4b CP - How can you use a wave tank to investigate the speed of waves?
- Set up a wave tank filled with water and a straight dipper with a ruler along the side
- Vary the voltage provided to the straight dipper till there are at least 2 waves visible at any point
- Count how many waves form in 10 seconds and divide by 10 to get your frequency
- Using the ruler estimate the wavelength of a wave
- Frequency x wavelength
- Alternatively, record how long it takes the wave formed to travel a certain distance and to distance/time
SP4b CP - How can you use a metal rod to investigate the speed of waves in solids?
- Suspend a metal rod using clamp stands
- Hold a smartphone with a frequency app at one end
- Hit the other end of the rod with a hammer and record the peak frequency
- Meausure the length of the rod
- Frequency x wavelength
SP4c - How does refraction occur?
- When a ray of light reaches an interface (boundary) between substances, it changes speed (because light’s speed is dependant on the density of the substance it travels in).
- If it slows down it bends towards the normal and if it speeds up it bends away
SP4c - Using water waves as a model, explain why refraction occurs.
- Waves of water travel faster is deeper water than shallow water
- They also are longitudinal so can be represented with lots of parallel lines rather than one line
- When the wave of water reaches a boundary between shallow and deep, the part of each line that is furthest ahead, will reach the boundary first and slow down first.
- This gradual change in which parts slow down means that the wave bends towards the normal
SP4d - What are the definitions of the following:
- Reflect
- Refract
- Transmit
- Absorb
- Reflect: The waves bounce off
- Refract: The wave passes into the new material but changes direction
- Transmit: The wave passes through without being absorbed or reflected
- Absorbed: The wave disappears as the enrgy it was carrying is transferred into the material
SP4d - Why is a prism able to split white light into a spectrum?
Each frequency of light changes speed at a slightly different rate meaning that at the right angles they can be split up
SP4e - Describe the process of a sound being heard by and ear. [6 marks]
- Sound waves enter the ar canal which focuses it
- The eardum is a thin membrance which vibrates due to the soundwaves’ vibrations
- Vibrations are passed on to tiny bones which amplify the vibrations
- Vibrations are passed on to the liquid inside the cochlea
- Tiny hairs inside the cochlea detect these vibrations and convert them to electrical impulses
- Impulses travel along the auditory nerve to reach the brain
SP4e - How does the cochlea work?
- The cochlea has a membrane covered with hair cells
- Each hair cell is connected to a neurone so that when it detects a vibration of its frequency it creates and electrical signal
- The cochlea is a spiral with the outmost part (the base) detecting hgih frequencies (up to 20000Hz) and the low end (the apex) detecting lower frequencies (down to 20Hz)
SP4e - Explain why as people get older, their range of hearing may decrease.
- As people get older, the hairs of the base and apex of their cochlea can get damaged.
- This means that they are no longer able to convert vibrations into impulses
- Thus they can’t hear these sounds
SP4f - What is the human range of hearing?
20Hz - 20,000 Hz
SP4f - What is ultrasound?
Sound above 20,000 Hz
SP4f - How can boats use ultrasound in sonar equipment?
- To find the depth of the water beneath them.
- They fire off an ultrasound wave at 1500m/s.
- They time how long it takes to return.
- They use d = s x t to find out the distance hte wave travelled and divide it by 2 to find the depth of the water
SP4f - How is ultrasound used in scans?
- A probe emits ultrasound waves
- Gel is used to stop it from reflecting
- Some waves are reflected when they meet bones, fat, tissue etc.
- The probe also detects these refelected waves
- It sends these as impulses to the computer
- The ultrasound imaging machine detcts the frequency of the impulses turning it into an image
SP4f - Why is an ultrasound scan more beneficial for scanning a foetus?
- Other scans such as PET and CT would release radiation
- This could harm the foetus causing mutations
SP4g - What is infrasound?
Sound below 20Hz
SP4g - What are the two types of seismic waves and what is the difference?
- P waves: Longitudinal
- S waves: Transverse
SP4g - What are seismic waves?
Vibrations produces by earthquakes
SP4g - Why are P waves more useful than S waves?
- P waves are longitudinal while S waves are transverse
- S waves can only be transmitted by solids but P waves can go through all through states
- The earth has a liquid outer core
- S waves fired from a point can’t go throuhg the liquid core but P waves can
- This means that S waves have a larger shadow zone
- Using the idea that S waves can’t go through liquids and P waves can, scientists were able to find out about the structure of the earth
SP4g - What is a shadow zone?
The area where a wave cannot reach when fired from a point
SP4g - What is the key thing to remember about seismic waves as they pass through the earth?
They get refracted
SP4g - Why may there still be weak P waves even in the shadow zones?
They can be reflected by the solid inner core
SP4g - How can seismic waves be used to detect earthquakes?
Seismic waves can be detected by seismometers and give information about where earthquakes are originating
SP5a - What two processes can be shown using a ray diagram?
- Reflection
- Refraction
SP5a - What do i and r represent in ray diagrams?
- i: Angle of incidence (between incident ray and the normal)
- r: Angle of reflection/refraction (between reflected/refracted ray and the normal)
SP5a - What is the relation between the angles of incidence and reflection/refraction?
i = r (Angle of incidence = angle of reflection)
This is the law of reflection
This is only for reflection and not for refraction
SP5a - What is the normal?
The line drawn perpendicular to the object light is reflecting off (or refracting through)
SP5a - Describe total internal reflection.
- TIR occurs when light refracts through a substance at sucha low angle of incidence that it doesn’t leave the other side
- This angle is called the critical
- If light enters at the critical, it will move along the interface
- If light enters at an angle smaller than the critical, it will cause TIR to happen
SP5a CP - Describe a method to explore refraction with varying angles of incidence,
- Place a ray box with a slit in front of it on a piece of paper
- Place a glass box the way of the ray of light thta is being produced
- Draw around the glass block
- Mark the point of entry and exit for the light aswell as two further points (such as origin and edge of paper) on the piece of paper
- Use your markings to draw lines representing the travel of the ray of light
- Repeat with ray box at different angles and compare your results
SP5b - What are the two types of reflection?
- Specular: When light is reflected evenly on a smooth surface
- Diffuse: When light is reflected in all directions on a rough surface
SP5b - Describe why a green object appears green in sunlight.
- Sunlight is made up of white light as it contains all the colours of the visible spectrum
- An object that appears green will reflect the green part of the spectrum but reflect all the other colours
SP5b - what effect would a blue filter have?
A blue filter would only transmit the blue part of the light that goes to it.
SP5d - What are the similarities between all EM waves?
- They are all transverse waves
- They all travel at (3x10^8m/s) ina vacuum
- They transfer energy
SP5d - How were infrared waves discovered?
- A prism was used to refract white light into the seven componenets.
- A thermometer was placed just outside of the red part of this spectrum.
- Another was placed in the spectrum.
- The thermometer next to red was warmer suggesting there was something warming it up
SP5e - List all the colours in the visible light spectrum.
ROYGBIV
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
SP5e - List all of the EM waves in order of increasing wavelength/decreasing frequency.
- Gamma rays
- X-rays
- Ultraviolet
- Visible light
- Infrared
- Microwaves
- Radio waves
SP5e - Why do different telescopes need to be used to study different EM waves?
EM waves of different length get absorbed by different amounts by the atmosphere
SP5f - What can infrared be used for?
- Heating food
- Short range communication such as TV remotes
- Security systems
SP5f - What can microwaves be used for?
- Communications and satellite transmissions
- Heating up food and giving it energy
SP5f - What can radio waves be used for?
- Transmitting radio broadcasts
- Radio communications via satellites
SP5f - How are radio waves produced?
- Oscillations in electrical signals.
- Metal rods can be used as aerials because they can absorb and transmit these oscillations
SP5f - Whay can radio waves be used for longer ranges than microwaves?
- The way radio waves and microwaves travel is dependant on the angles they reach the ionosphere.
- At all angles, microwaves pass straight through and so there is maximum range they can be fired in a straight line.
- At some angles, radio waves are reflected by the ionosphere, becasue they have larger wavelengths.
- This means they don’t have to be fired directly to a point
SP5h - What are the uses of Ultraviolet rays?
- Disinfect waters by killing microorganisms
- Invisible ink due to fluoresence
- Security on bank notes
SP5h - What are the uses of x-rays?
Imaging of the inside of the body
SP5h - What are the uses of gamma radiation?
- Radiotherapy
- Sterilisation of medical equipment and food
- PET scanner
SP5i - What are the dangers of infrared radiation?
- Infrared radiation is absorbed by our body.
- We feel it as heat and an excess of it can destroy cells burning skin
SP5i - What are the dangers of ultraviolet light?
It can cause sunburn and damage to DNA which can lead to skin cancer
SP5i - What are the dangers of x-rays and gamma rays?
They can lead to mutations causing cancer.
SP5i - Why are UV x-rays and gamma rays dangerous?
- They are ionising radiation.
- They large amounts of energy due to high frequencies and short wavelengths which can pass through our skin.
SP5g - What is the difference between a hot and cold object in terms of radiation?
- All objects emit the same amount of radiation that they absorb.
- Hotter objects will emit more radiation than cold objects in the same time
SP5g - For the earth’s temperature to stay constant what must happen?
The amount of radiation it absorbs from the sun must be equal to the amount of radiation that the earth radiates into space
SP5g - Describe the greenhouse effect in terms of radiation.
- Energy from the sun is absorbed by the earth.
- The earth radiates this into the atmosphere
- Greenhouse gases in the atmosphere absorb this energy keeping it in the atmosphere
- This means that the earth doesn’t radiate into the atmosphere the same amount of energy it absorbed
- Thus the temperature of the earth rises
SP5g CP - Describe an experiment to explore how different surfaces absorb and emit infrared radiation using the following surfaces:
- Shiny black
- Shiny silver
- Dull black
- Dull grey
[Don’t worry guys its not just you I’m pretty sure we haven’t done this one]
- Pour water at 80° into four boiling tubes
- Cover each with one of the surfaces
- Put a thermometer in each
- Time it and record the temperautre at regular intervals
- The one that has the largest drop in temperature emits the most energy and thus must also absorb the most energy
- You would expect the results to be from largest to smallest change:
- Dull grey
- Dull black
- Shiny black
- Shiny silver
SP5c - What is a lens, and what is its power?
A lens is a small piece of transparent material made to refract light in a certain way
The power of a lens is how much it refracts light and is dependant on the shape and thickness of the lens
SP5c - What is the difference between a converging (convex) and diverging (concave) lens?
- Converging: Fatter in the middle and thinner at the top and bottom. Rays of light converge onto a focal point
- Diverging: Fatter at the top and bottom and thinner in the middle. Rays diverge away from each other once they pass through
SP5c - What does F mean on a ray diagram?
F is the focal length, i.e the length between the lens and its focal point
SP5c - When an object is placed more than 2F from a converging lens, what happens?
- Real image
- Inverted
- Less than 2F from other side of lens
- Smaller size
- (camera, eyes)
SP5c - When an object is placed at 2F from a converging lens, what happens?
- Real image
- Inverted
- 2F from other side of lens
- Same size
- (Photocopier)
SP5c - What happens when an object is placed between 2F and F from a converging lens?
- Real image
- Inverted
- More than 2F from other side of lens
- Larger size
- (Projector)
SP5c - What happens when an object is placed less than F from a converging lens?
- Virtual image
- Right way up
- Further than F on the same side of the lens
- Larger size
- (Magnifying glass, mirror)
SP5c - What happens when an object is placed more than F from a diverging lens?
- Virtual image
- Right way up
- Less than F on the same side
- Smaller size
SP5c - What is the difference between real and virtual images?
Real images:
- Can be projected onto a screen
- Same way round
- Appears on the opposite side of the lens
- Only produced by converging lenses
- e.g. Projectors
Virtual images:
- Can’t be projected onto a screen
- Inverted (left-to-right)
- Appears on the same side of the lens
- Produced by diverging and converging lenses depending on situation
- e.g. Mirrors
SP5c - What is the focal point of a lens?
The point where all the rays of light would converge onto and meet.
SP6a - What did the plum pudding model look like?
Made of positively charged mass with negatively charged electrons scattered throughout.
SP6a - What was the experiment that Erenest Rutherford conducted and what did he do?
- The gold foil experiment.
- He fired alpha particles through various substances e.g. thin gold foil.
- Firing alpha particles from a source and having a detector behind whatever substance he used so that he could find out if the particles pass through.
SP6a - What were the results drawn of the gold foil experiment and what conclusions were drawn from this?
- Most particles passed straight through
- Some were deflected slightly
- Others were bounced back
- This means that most of an atom is empty space.
- Aditionally, atoms have a concentrated area of positive charge.
- This is why some were reflected back.
SP6a - What is the radius of a nucleus and the radius of an atom?
- N: 1x10-15
- A: 1x10-10
(Atom is 10,000 times bigger)
SP6b - What are the charges, locations and relative masses of protons neutrons and electrons?
P:
- Inside nucleus
- +1 charge
- mass of 1
N:
- Inside nucleus,
- no charge
- mass of 1
E:
- Orbiting nucleus
- -1 charge
- mass of 1/1835 (negligible)
SP6b - What does the atomic number of an atom represent?
- The number of protons in the nucleus.
- Different elements have different proton numbers
SP6b - What does the mass number of an atom represent?
- The mass of the atom.
- Protons plus neutrons.
SP6b - What is an isotope?
Two atoms of the same element with different masses (Same atomic number but different mass numbers)
SP6c - What can happen if an atom gains enough energy and what does this create?
- An electron can move to a higher orbit.
- When it returns back to its orbit it emits energy in the form of visible light.
- The wavelength (and therefore colour) depends on the change in orbit.
SP6c - What do we use to see the light produced by an atom?
- An emission spectrum.
- A black line spectrum with coloured lines along it displaying which wavelengths were emitted.
SP6c - How will the emission spectrum of an element relate to its absorption spectrum and what does this tell us?
- The coloured areas on the emission spectrum will be blacked out on the absorption spectrum and vice versa.
- This means that the wavelengths that are emitted are also the wavelengths that are absorbed.
SP6c - If an atom gains more energy than needed to just move an electron to another orbit, what can happen and what is this called?
- The atom can loose an electron.
- This is called ionisation as the atom has become an ion
SP6c - What is an ion?
An atom that is charged due to a gain or loss of electrons.
SP6c - What do we call radiation that causes an atom to loose an electron?
Ionising radiation
SP6d - What is background radiation?
Radiation that is constantly all around us at a safe level.
SP6d - What are the six main sources of background radiation
- Medical
- Ground and buildings
- Food and drink
- Radon gas
- Cosmic rays
- Nucelar
SP6d - Which source of backgrond radiation accounts for most of it and approximately how much is it?
Radon gas just under 50%
SP6d - What are ways of measuring radioactivity?
- With a Geiger
- Mueller tube / counter Meausres the count rate
- Photographic film (badges called dosimeters) Gets darker / changes colour as its exposed to more radioactivity
SP6d - Before measuring the radioactivity of a source what must be done?
Measure the background radiation so you can take this away from the radiation that you measure or else you value will be the source’s radiation + the background radiation.
SP6e - What is an alpha particle?
A helium nucleus consisting of 2 protons and 2 neutrons
SP6e - What is a beta minus particle?
An electron
SP6e - What is a beta plus particle?
A position (A positive electron)
SP6e - What don’t gamma rays have that other radiation does.
Since it is an EM wave and not a particle, it doesn’t have a charge.
SP6e - Rank and explain the types of radiation in terms of ionisation.
- Alpha (Most)
- Beta (+/-)
- Gamma (Least)
Since alpha particles are emitted at high speeds thay carry most energy and are best at ionistation.
This is the opposite for Gamma.
SP6e - Rank the types of radiation in terms of penetration / range.
- Gamma (Most)
- Beta (+/-)
- Alpha (Least)
SP6e - What does it take to stop each type of radiation?
- Alpha: paper/skin/few cm of air
- Beta: few m of air/3mm of alluminium
- Gamma: few Km of air/ few cm of lead/ several m of concrete
SP6f - What occurs in alpha decay?
An unstable nucleus looses 2 protons and 2 neutrons (an alpha particle) causing its mass number to decrease by 4 and its atomic number to decrease by 2.
SP6f - What occurs in beta minus decay?
A neutron decays into a proton and a high energy electron.
SP6f - What occurs in beta plus decay?
A proton decays into a neutron and a high energy positron.
SP6f - What occurs in gamma decay?
An unstable nucleus emits a gamma ray becoming more stable.
SP6g - What is a half-life?
- The time it takes for half the unstable nuclei of a substance to decay
- The time it takes for the count rate of a radioactive substance to decrease by half.
SP6g - If a substance has a half-life of 2 minutes and has a count rate of 128Bq, what will its count rate be after 8 minutes?
8/2 = 4
24 = 16
128/16 = 8
8Bq
SP6h - How might you use radiation to treat food?
Irradiating fresh produce makes it safer to eat and increases its life time.
SP6h - How might radioactivity be used in hospitals?
- To detect and treat cancer (radiotherapy and PET scans)
- To sterelise equipment
SP6h - How may radioactivity be used when a pipe leaks?
- A gamma source is added to water and passed through the pipe and a geiger tube is placed on top.
- Areas with leaks have higher levels of radiation.
SP6h - When making paper, how may radioactivity be used?
- A beta source is placed on one side of the paper and a detector on the other.
- When the detector detects too few beta particles passing through, the paper is too thin and so adjusts the force applied to the paper.
- When too many pass throught the opposite happens.
SP6i - What is it called when the DNA inside a cell is damaged by ionising radiation?
Mutation
SP6i - Why do mutations in cells have long term effects?
Because they can be passed down through generations
SP6i - How may someone hande radioactive sources safely?
- Using tongs
- Not pointing the source at people
- Storing the source in lead lined containers
SP6i - How do medical staff reduce their exposure to radioactive sources?
- Increasing their distance
- shielding the source
- Minimising time spent near the source
- Wearing dosimeter badges to monitor exposure
SP6i - What sort of sources are used when treating cancer patients?
Ones with short half - lives
SP6i - What is the difference between irradiation and contamination?
A substance becomes irradiated if exposed to a radioactive source but is contaminated if it is still radioactive even when the source is taken away.
SP6i - How may a nuclear accident affect food supply?
- Water and soil nearby gets contaminated which contaminates the crops and plants.
- Animals that feed on this also become contaminated,
SP6j - How may a gamma camera be used in medical diagnosis?
- A radioactive tracer with a short half - life is injected into the blood stream.
- The gamma camer detects areas of high radiation.
- This can help in diagnosing internal bleeding.
- The tracer is made using radioactive glucose molecules because cancer cells take up glucose quickly.
SP6j - How does a PET scan work?
- A tracer that has beta plus decay is injected into the patient.
- When the emitted positron meets an electron, they annihilate each other and release two gamma rays in opposited directions.
- The PET scnanner moves around the patient detecting where gamma radiation originates from forming a series of images.
SP6j - What is internal radiotherapy and what are the pros and cons?
A beta emitter is placed next to the tumour inside the body.
SP6j - What is external radiotherapy?
Several beams of gamma rays, X-rays or protons are fired at the tumour from multiple directions.
SP6j - Why is external radiotherapy preffered to internal radiotherapy?
Internal radiotherapy can harm can harm healthy cells while external radiotherapy specifically targets the cencer cells. Internal radiotherapy is only used in situations where the benefit greatly exceeds the risk.
SP6k - What are the pros and cons of using nuclear energy over fossil fuels to generate energy?
Pros:
- Sources of uranium will take a lng time to expire
- They store mre energy per kg
- They cause less deaths
- The stations themsleves don’t release GH gases
Cons:
- The extraction process release many GH gases
- Waste substances can contaminate environment if not stored properly
- Very expensive to decomission safely
- Nuclear accidents cause many deatsh and long term effects
SP6l - What is nuclear fission?
When an unstable nucleus absorbs a neutron, it decays releasing two smaller daughter nuclei, neutrons and energy.
SP6l - If the neutrons released by nuclear fission go on to cause another nucleus to decay, what is this called?
A chain reaction
SP6l - What are the jobs of the moderator and the control rods in a a reactor?
- CR: Rods that contain elements that absorb neutrons. Can be lowered or raised to control how much reation is taking place and how much energy is generated.
- M: Material which slows down neutrons. This allows the neutrons to be absorbed increasing rate of reaction
SP6l - How does the energy generated fin a nuclear reactor get transferred into electrical energy?
- Thermal energy is generated from the reaction process.
- This is used to heat up a source of water turning it into steam.
- This steam turns turbines which turn and power the generator generating electricity.
SP6m - What is nuclear fusion and where does it take place?
Nuclear fusion occurs when two smaller nuclei (typically hydrogen) join together to form a larger atom (helium) and energy in the form of gamma radiation
SP6m - What conditions are needed for nuclear fusion to occur and why?
- Nuclear fusion requires that the nuclei are travelling at over 1,000,000 m/s and in temperatures hotter than the sun.
- This is to overcome the electrostatic repulsion that would otherwise repel the two like charged nuclei away from each other.
SP6m - Why aren’t there any working nuclear fusion stations?
To maintain conditions required to overcome elctrostatic repulsion is extremely costly and hard to sustain on earth.
SP7a - What is the geocentric model?
The model of our solar system in which everything orbits the earth.
SP7a - What is the heliocentric model?
The current model of our solar system where the sun is at the centre and other planes orbit it.
SP7a - What shape is the earth’s orbit around the sun?
Elliptical
SP7a - What developments in techonology have allowed us to make more detailed observations?
- Computers allow detailed analysis.
- Photography allows accurate and permanent storage of events.
- Telescopes can now be place outside of the earth’s atmosphere giving wider and more detailed detection.
- Space probes allow better analysis of the solar system.
SP7a - Why are telescopes place outside the earth’s atmosphere more detailed than a regular telescope?
- The earth’s atmosphere absorbs many waves of the EM spectrum.
- Outside the atmosphere, these could be detected. (such as infrared radiation)
SP7b - What is the difference between weight and mass?
Your weight is the force acting on you dependant on your mass and the gravitational field strength.
SP7b - What is the gravitational field strength on earth?
9.81 N/Kg
(Can be rounded to 10N/Kg)
SP7b - What are the four types of orbits for artificial satellites?
- Highly elliptical
- Circular geostationary
- Low earth orbits
- Polar orbits
SP7b - What is a geostationary orbit and what are these satellites used for?
- Satellites that stay in the same place relative to the earth’s position.
- They move at 3070 m/s and are used for broadcasting.
SP7b - A satellite in which type of orbit will eventually pass over all parts of the earth?
Polar orbits
SP7b - A satellite in which type of orbit needs the least fuel for launching?
Low earth orbits
SP7b - A satellite in which type of orbit is used for communication with parts of the earth near the poles?
Highly elliptical orbits
SP7b - Why doesn’t a satellite continue moving in a straight line?
The gravitational force between the earth and the satellite causes it to continuously change direction and orbit the earth.
SP7b - At what angle is the force between the earth and satellite?
90°
SP7b - Explain the speeds that a satellite would have to be travelling at in relation to its orbit, and the changes in orbit it would experience if it changed speed.
- The gravitational force on an object in a lower orbit is a stronger than at a higher orbit so a satellite at a lower orbit would have to travel at a higher speed to stay in orbit.
- Once it eventually slows down, it will drop towards earth.
- However as it drops it gains speed and will eventually be able to be at a lower orbit at a faster speed.
- Once it drops enough that it passes through the earth’s atmosphere, the air resistance will slow it down and it will eventually fall to earth.
SP7b - What reaction takes place inside a star?
Nuclear fusion
(typically H + H = He)
SP7b - Describe the life cycle of a star the size of our sun. [6 Marks]
- It starts with a Nebula (A cloud of gas).
- The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar.
- Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium
- The energy released form the fusion reactions push the star outward causing it to expand.
- Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium
- Eventually, hydrogen runs out and heavier reactions take place.
- This creates more energy which expands the star more
- The outermost layers are no longer held in place by the force of gravity so they expand forming a red giant
- Once all the fuel has run out, all the layers disband forming a shell of gas.
- This leaves behind a highly dense white dwarf which doesn’t carry out any reactions.
SP7b - Describe the life cycle of a star much larger than our sun. [6 Marks]
- It starts with a Nebula (A cloud of gas).
- The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar.
- Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium
- The energy released form the fusion reactions push the star outward causing it to expand.
- Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium
- Eventually, hydrogen runs out and heavier reactions take place.
- This creates more energy which expands the star more forming a red supergiant.
- These heavier fusions are carried out all the way to iron when it runs out of fuel.
- The star rapidly collapses causing a supernova
- This leaves behind a very dense neutron star
- If the mass of the star is even larger, then a black hole is formed in place of the neutron star.
SP7d - What is the doppler effect?
When the pitch of a noise get lower as it travels aways from you. (and higher when it travels towards you)
SP7d - Why does the doppler effect occur?
As a sound travels, the wavelengths are squashed or stretched meaning the sound’s pitch appears higher or lower.
SP7d - What is red-shift?
When light form distant galaxies shift towards the red side of the spectrum due to wavelengths being stretched as the galaxy moves away from earth.
SP7d - What do we use to check red-shift?
Absorption spectrums of the galaxy compared to the absorption spectrum of the sun.
SP7e - What are the two main theories for the origin of the universe?
- The big bang theory
- Steady state theory
SP7e - What is the Big Bang Theory?
- The whole universe started out from one point of concentrated energy.
- All matter started form this point and continued to expand outwards as the universe constantyl expands.
SP7e - What is the Steady State Theory?
The universe always existed and as it expands matter is continuosly created.
SP7e - Which theory of the universe is the currently accepted theory?
The Big Bang Theory
SP7e - What provides evidence for both theories of the universe and why?
Red-shift; as galaxies are constantly moving away the universe is constantly expanding.
SP7e - What provides evidence for the currently accepted theory.
CMBR (Cosmic Microwave Background Radiation) is found throughout all of the universe at the same rate suggesting that it all started form one point and expanded out from there.
SP7e - What can we use as a model of why CMBR proves The Big Bang Theory?
- A Currant bun has currants close together.
- As the dough rises, the number of currants stay the same but they are found at consistent rate throughout the bun.
SP7d - What does it mean if one galaxy has a greater red-shift than another?
That galaxy is further away and moving faster than the other.
