Physics Revision Flashcards
Energy
something that cannot be created or destroyed, only transferred from one source to another
Nuclear Energy
energy inside the nucleus of an atom
Elastic Potential Energy
energy inside things that can stretch
E = 0.5 x k x e^2
Chemical Energy
energy from chemical reactions
Gravitational Potential Energy
energy in gravity
Kinetic Energy
energy in things that move, such as people’s bodies and also sound
KE=1/2mv^2
Magnetic Energy
energy in magnets
Thermal Energy
energy of heat
Open System
systems which interact with their environment, so that energy or mass can be added or removed from them
Closed System
an isolated system in which no energy transfers take place out of or into the energy system
Mechanical Transfer
happens in things like cycling
Electrical Transfer
happens in things like static electricity
Transfer by Heating
happens in things like boiling eggs
Transfer Through Radiation
happens in things like sound waves
Work Done
force x distance
energy transferred
Efficiency
a measure of how good a device is at changing energy from one form to another
Power
energy transferred in a given time
power = energy transferred/time taken
Conduction
transfer between particles in a solid
Conductor
a substance that conducts heat, such as a lightening rod on the side of a building
Conductivity
the power of heat conduction
Insulator
a bad conductor whose particles are too far apart to allow energy to flow between them, such as liquids, gasses and vacuums
Density
mass per unit volume
Melting
transfer from solids to liquids
Freezing
transfer from liquids to solids
Boiling
transfer from liquids to gasses
Condensing
transfer from gasses to liquids
Temperature
a measure of the average kinetic energy of the particles in an object
Internal Energy
the sum of all the kinetic energy the individual particles have from moving relative to each other and the potential energy that individual particles have because of their positions relative to each other in a substance
Unstable
an element becomes unstable if there are too many protons or neutrons, in an attempt to stablise itself, it omits radioactivity, decaying
Background Radiation
a type of relation that is always present around us, but with very low doses, which is safe, including underground rocks, food, cosmic rays from the sun and industrial uses
Radius of an atom
1x10^-10
Ionisation
any process by which atoms become charged
Irradiation
when an object is exposed to ionising radiation and the object does not become radioactive
Contamination
the unwanted presence of materials containing radioactive atoms on other materials, due to the decay of contaminating atoms
Decay
where a radioactive nucleus gives out alpha, beta or gamma particles
Alpha Decay
releases 2 protons and 2 neutrons
Beta Decay
gains a proton
Alpha Particle
the same as a helium nucleus
Beta Particle
the same as a high-energy electron
Alpha
two protons, two neutrons, stopped by a sheet of paper, very high ionising ability, slow speed, positive charge
Beta
electron, medium ionising ability, stopped by 5mm aluminium, negative charge, fast
Gamma
electromagnetic wave, least ionising, stopped by thick concrete, no charge, travels at the speed of light
Speed of Light
3x10^8mps
Half Life
the time it takes for the count rate to halve
Activity
the number of unstable atoms that decay per second in a radioactive source, measured in Bacquerei
Net Decline
the overall amount that the activity of a source has fallen in a period of time
Gamma Knife
used to treat cancers, small doses are targeted at the tumour from a moveable box, concentrated on the tumour
Radioactive Tracers
used in medicine to trace the flow of a substance through an organ
Radioactive Implants
used to destroy cancer cells in some tumours
Nuclear Fission
involves isotopes being split up, releasing energy
Nuclear Fusion
involves isotopes being joined together, releasing energy
Induced Nuclear Fission
occurs when a stable isotope is struck by a neutron, where the isotope absorbs the neutron, becomes unstable and splits into smaller fragments, releasing neutrons and energy
Nuclear Bombs
uncontrolled fission reactions
Chain Reaction
where one fission reaction goes on to cause several more
Spontaneous Nuclear Fission
roughly the same as induced, but happens without a neutron being absorbed
Static Charge
where an insulator is charged up by friction, causing electrons to either be rubbed onto or rubbed off the object causing them to be charged, only the negative charge move
Earthing
the process in which electric energy is instantly discharged directly to the earth through a low resistance wire, e.g. lightening wires, reducing risk of electric shock as energy is transferred down the wire quicker than it could anyone
Pipe Earthing
when electricity is sent down a pipe to the ground
Plate Earthing
when electricity is sent into an underground plate
Series Circuit
increasing voltage makes lights brighter, adding an extra bulb makes lights dimmer, unscrewing one breaks the circuit, current stays the same, potential difference is shared
Parallel Circuit
increasing voltage makes bulbs brighter, adding an extra bulb has little effect, unscrewing one bulb has no effect on other bulbs, current is shared, potential difference stays the same
Ammeter
measures current, must be in series with the component you are measuring
Voltmeter
measures potential difference, must be in parallel with the component you are measuring
Current
rate of flow of electrons
Conventional Current
flows from positive to negative, whilst electrons flow from negative to positive
Energy Transferred
E = VxQ
Potential Difference
V = IxR
Ohm’s Law
current is directly proportional to voltage when the temperature of the conductor is constant
Light Dependent Resistor
resistance decreases when light intensity increases
Thermistor
resistance decreases when temperature increases
Direct Current
current from cells and batteries which always flows in the same direction
Alternating Current
current from the mains, which is constantly changing direction
Oscilloscope
allows a visual representation of electrical signals, such as sound signals or electrical signals from someone’s heart
Amplitude
the top of a wave on an oscilloscope
Frequency
amount of waves per second
Period
time for one wave
Fuse
a thin piece of wire that gets hot and blows if too high a current flows, breaking the circuit and preventing fires
Residual Current Circuit Breaker (RCCB)/Residual Current Device (RCD)
resettable fuses, usually found in homes, which are more sensible than plug fuses
Neutral Wire
the blue wire, goes on the left
Live Wire
the brown wire, goes on the right
Earth Wire
the yellow and green wire, goes through the middle, connects to the metal case of an appliance, occurs when the current flows down from the earth wire instead of through you if you touch it, prevents electric shock
Plugs
contains the cable, cable grip, three wires and a fuse, made of copper because it is flexible, brass because it’s an alloy, strong and durable, copper because it is a good conductor, plastic because it is an insulating, hence a casing
Double Insulation
improves safety by making sure an item that has two plastic cases without any wires touching the case, meaning the case cannot become live, because plastic does not conduct electricity, meaning that if one layer of insulation is damaged, the appliance is still safe for use
Power
P = I x A x V
P = I x A^2 x R
P = E/t
National Grid
a system of transformers and cables
Step-up Transformer
increases the potential difference, which reduces energy loss in transmission cells
Step-down Transformer
reduce the potential difference before the electricity crosses to homes
Scalar Quantity
a quantity that has magnitude but no specific direction
Vector Quantity
a quantity that has magnitude and a specific direction
Resultant Force
the net force acting, the sum of all forces acting on the object
Contact Force
something like air resistance, which involves contact
Non-Contact Force
something like gravity, which doesn’t involve contact
Parrallelogram of Forces
used to work out resultant forces where forces don’t just go up and down
Equilibrium
when forces have no overall turning effect, meaning the resultant force is often zero
Force
N = J/m
Gravity
N/kg = N/kg
Hooke’s Law
states that the extension of a spring is directly proportionate to the force applied, provided its limit of proportionality is not extended
Spring Constant
K = F/e
Elastic Limit
point where object has stretched more than expected and can no longer return to its normal shape
Speed
how fast something is going
distance/time
Velocity
speed and direction
distance/time
Isotope
atoms of the same element with a different number of neutrons
Energy Levels
electrons are arranged at different distances from the nucleus called energy levels or shells
Sieverts
the unit for measuring radiation doses
Particle Physicist
someone who studies the part of physics that relates to particles
Geiger Counter
used to measure the amount of radioactivity in the air
Distance
a scalar quality that describes how far an object moves
Displacement
includes both the distance an object moves, measured in a straight line form the start point to the finish line, and the direction of that straight line, a vector quality
Average Walking Speed
1.5 m/s
Average Running Speed
3 m/s
Average Cycling Speed
6 m/s
Average Train Speed
100 km/h
Average Plane Speed
900 km/h
Acceleration
measured in m/s^2
a = v/t
Uniform Acceleration
(final velocity)^2 - initial velocity)^2 = 2 x acceleration x distance
v^2 - u^2 = 2as
Ohmic
where resistance remains constant as current changes
Particle Acceleration
apparatus for accelerating subatomic particles
Van de Graaff
generator that uses an electric belt to accumulate charge
Ion
a charged atom
Concrete Shield
protective barrier to stop objects outside getting contaminated
Control Rods
absorbs stray neutrons, making sure the reaction stays under control, can be moved in and out depending on how many neutrons need to be absorbed
Fuel Rods
made of a form of Uranium
Heat Exchanger
full of steam which falls down and becomes water as it cools
Pump
controls the amount of water in the reactor at any one time
Turbines
driven by steam heated by the nuclear power, which condenses into water and goes through the reactor all over again
Steel Vessels
contain the stuff for the nuclear reactor, steel to make sure contamination doesn’t happen
Reactor Core
the most important part of the reactor, where the nuclear bit happens
Pressuriser
regulates coolant pressure in the nuclear reactor
Newton’s First Law
states that if forces are balanced on an object, it either does nothing or continues to do what it’s doing
Newton’s Second Law
states that if you increase forces, something goes faster
Resultant Force = mass x acceleration
Newton’s Third Law
states that all forces have an equal and opposite force
Inertia
a tendency of an object to remain unchanged, or continue in an existing state
Terminal Velocity
acceleration of a falling object acted on only by gravity
0
Reaction Time
0.2 - 0.9 seconds
Conservation of Momentum
in a closed system, the total momentum before an event is equal to the total momentum after the event
Earth’s gravitational field strength
9.8N/kg
Stopping Distance
thinking distance + braking distance
Thinking Distance
stopping distance - braking distance
Braking Distance
stopping distance - thinking distance
Crumple Zone
part of a car that increases the impact time, lessening the impact force
Kilo
10^3
milli
10^-3
Mega
10^6
micro
10^-6
Giga
10^9
Nano
10^-9
Tachographs
devices in long-distance vehicles that monitor driving time, speed and distance
Neutrino
a particle able to travel faster than the speed of light
Systematic Error
an error that causes the same problem to all pieces of data such as something causing every piece of data to be 30 seconds off
Personal Error
an error caused by a person’s habits, a type of systematic error
Random Error
an error that affects only one result, such as misreading the scale once
Ultrasound
sound above the maximum frequency that humans can hear
20000Hz
Pascal
N/m^2
Pressure
Force / Area
Fluid
Liquid or gas
Pressure due to a column of liquid
Pressure = column height x density of liquid x gravitational field strength
Pascal vases
vases that show how liquid flows until the pressure along the same horizontal level is constant
Atmosphere
a thin layer relative to the size of the Earth around the Earth
Atmospheric Pressure
air molecules colliding with a surface
Upthrust
the force on an object in a fluid, that is equal to the weight of the fluid displaced
volume of body submerged x density of liquid x acceleration due to gravity
Boiling Point
the point at which vapour pressure equals atmospheric pressure
Vapour Pressure
the pressure exerted by the gas when the amount of particles leaving the liquid equals the amount entering the liquid
Earth’s atmospheric pressure
101325Pa
Gears
rotating wheels with teeth that interlock with each other used to transmit and often multiply rotational forces, hence they act in a similar way to levers
Centre of Mass
the point at which the mass of the body may be thought to be concentrated
Driven Gear
gear that is moved
Driving Gear
gear that does the moving
Idle Gear
gear between driving and driven
Plumb Line
mass on a string that hangs vertically
Period
time taken for a pendulum to swing
Point of Balance
must be directly above the centre of mass
Pivot
the point at ninety degrees to the force which the turning happens around
Newton metres
measurement for moments
Moment
turning effect of a force
force x distance
Total clockwise motion
same as total anticlockwise motion
Lever
something to amplify the force, meaning it exerts a greater force than that applied by the effort
Gear
something to change the force or rotational speed of a system
Effort
the force exerted on the lever
Load
the amount being moved
Principle of Moments
the moment of any force is equal to the algebraic sum of the moments of the components of that force
Stability
a measure of the body’s ability to maintain its original position
Vibrations
a constant repeated back and forth or up and down motion
Wave
a series of disturbances that are the same distance from each other and transfer energy from one place to another
Mechanical Wave
waves which need a medium (e.g. sound waves, water waves)
Electromagnetic Wave
waves which do not need a medium (e.g. light waves)
Transverse Wave
a wave where the vibration are perpendicular to the direction of the energy transfer
Longitudinal Wave
a wave where the vibrations are parallel to the direction of energy transfer
Peak
the top of a wave
Trough
the bottom of a wave
Undisturbed position
Midpoint between the peak and the trough
Compression
area where longitudinal waves are close together
Wave Speed
wave speed = frequency x wavelength
the speed at which the energy is transferred, or the waves moves, through the medium, measured in metres per second, m/s
Ripple tank
a specialised form of wave tank used for demonstrating basic properties of waves
Incident Rays
the original rays
Reflected rays
rays that are reflected
Normal
the point at which incident rays are reflected and become reflected rays
Angle of incident
the angle at which an incident ray hits the normal
Angle of reflection
the angle at which a reflected ray leaves the normal
The Law of Reflection
the angle of incidence = the angle of reflection
Ray Diagrams
diagrams used to show rays and how they are reflected
Sound of Speed in Air
330m/s
Outer Ear
the external part of the ear that directs sound waves
Ear Canal
pathway from outer ear to eardrum
Cochlea
convert auditory signals to neural impulses
Ear Drum
thin membrane that is vibrated by sound waves
Auditory Nerve
nerves that allow you to hear
Hammer
small bone in the ear that vibrates to allow you to hear
Anvil
small bone in the ear that vibrates to allow you to hear
Stirrup
small bone in the ear that vibrates to allow you to hear
Pure Note
a note with constant frequency and amplitude
Impure Note
a note with inconsistent frequency and amplitude
Oscillation
repetitive vibrations
Oscillating
something that is vibrating
Visible Spectrum
consists of all the light we fan see: red, orange , yellow, green, blue, indigo, violet. Red is the longest wavelength and is refracted the least, whereas violet is the shortest wavelength is and is refracted the most
Infared
wavelength beyond red that we can’t see, refracted less than red and its wavelength is longer
Ultraviolet
wavelength beyond purple that we can’t see, it is refracted more than violet and its wavelength is shorter
Ionosphere
layer of the atmosphere that reflects radio waves
Aerial
a long wire that produces radio waves when an oscillating current is passed down it
Optical Fibres
fibres that light van be passed down, used in endoscopies and colonoscopies
Endscope
contains two bundles of fibres that transmit light into a body cavity for medical examination
Radar
radio wave
Sky TV
radio wave
SAT NAV
microwave
Bluetooth
radio wave
Light house
visible light
Mobile phone
microwave
Remote control
infa red
Distress singals
visible light
