Physics Definitions

Rate of change of displacement over time

The force when a mass of 1kg is accelerated by 1m/s/s

Where the mass of an object is focused

Where the force appears to act

Force x the perpendicular distance from the pivot

For a body in rotational equilibrium the sum of the clockwise moments is equal to the sum of the anti clockwise moments about the same point

The up thrust exerted on a body fully or partially surged in fluid is equal to the weight of fluid that body displaced. P=hpg

Force x distance moved

Total energy in a closed system remains constant, energy can never be created nor destroyed

The rate of work done P=W/t

The extension of a spring is directly proportional to the force exerted on that spring

E= half Fx. Its the area under a force extension graph

Force / cross sectional area

Extension / original length

Tensile stress / tensile strain

Take measurements of the length the cross-sectional area and the tensile force acting on the wire using the equation f = mg. Measuring the extension as a result of the mass we can then calculate Young's modulus

An object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force

When two objects interact they exert equal and opposite forces on each other

When two objects interact the total momentum in a specified Direction remains constant as long as no external forces act on the system

The net force acting on an object is directly proportional to the rate of change of its momentum

the product of force and time for which this force acts on an object equal to the change in momentum

The oil drop experiment is where he managed to levitate charged oil droplets between two oppositely charged metal plates by balancing the weight of the negatively charged droplet acting downwards with an upwards attractive Force from the positively charged plate

The sum of the currents in to that point is equal to the sum of the current out of that point

1 volt is the potential difference across a component when one joule of energy is transferred per unit charge passing through the component

The energy transferred from chemical energy or another form to electrical energy per unit charge

Electrons are released from the surface of a hot filament cathode after gaining enough kinetic energy. They are then accelerated towards an anode via and accelerating potential difference creating a beam of electrons with specific kinetic energy but can be altered by changing the potential difference

When internal factors such as temperature remain constant the current in the wire is directly proportional to the potential difference across it

An electrical component which only allows a current to flow in one particular Direction

The resistivity of a material at a given temperature is the product of the resistance and the cross sectional area divided by the length

The number density of free moving electrons in conductors is very high semiconductors medium and insulators very low

Negative temperature coefficient meaning that resistance drops as the temperature increases

The resistance varies depending on the conditions of the room for example in dark conditions the LDR has very high resistance and in light conditions the LDR has a very low resistance

P = I^2R P=V^2/R

The energy transferred by a device with power of 1 kilowatt operating for a time of 1 hour

The sum of the electromotive forces is equal to the sum of the potential differences around the closed loop

E=I(R+r)

Vout=V in x R1/R1+R2

an oscillation that travels through matter transferring energy from one point to another

The difference between the displacement of particles along a wave or on different waves

When they have a phase difference of 180 degrees or pi radians

When a wave changes Direction as it changes speed passing from one medium to another

When waves pass through a gap or travel around an obstacle they spread out

Particles oscillate along One Direction Only

The power passing through a surface per unit area

Intensity is directly proportional to the amplitude squared

400 to 700 NM

The angle at which light strikes the boundary must be above the critical angle and must be travelling from a denser medium to a less dense medium

When two waves interact the individual displacements are added

When superposition occurs between two waves with similar displacement

When two waves interact having opposite displacements

The difference in distance travelled between two adjacent waves

A beam of monochromatic light is passed through two adjacent slits creating a diffraction pattern on the back screen. It appears as alternating bright and dark regions called fringes successfully proving the wave nature of light

Waves which have no net transfer of energy

Wavelength increases from a half wavelength in intervals of half wavelength

Wavelengths starting at a quarter wavelength and increasing of in intervals of half wave lengths

Wavelength starting at half wavelength increasing in intervals of half wavelengths however there must be an antinode at each end

A tiny packets of electromagnetic energy

When electromagnetic radiation incident on the surface of a metal causes electrons to be emitted

When negatively charged the gold leaf is repelled away from the metal stem and when UV light is incident on the Zinc plate the photoelectric effect removes electrons returning the gold leaf to its former position

The minimum required frequency of the incident radiation in order for photoelectrons to be emitted

Increasing the Frequency means that emission of photoelectrons is faster and more instantaneous while increasing the intensity of the beam will only increase the maximum kinetic energy of each photoelectron

The minimum energy required to free an electron from the surface of the metal

The idea that all matter can be represented in particle or wave nature

The wavelength is directly proportional to the inverse of its momentum and equal to Planck's constant divided by its momentum

Given a specific temperature and pressure a substance can exist in all three phases of matter at once

A measure of the total internal energy of a substance

If two objects are in thermal equilibrium with each other and you add a third they are all in thermal equilibrium with each other

-273.15 it is the point at which the internal energy of a substance is 0

The arrangement of particles in solids liquids and gases

The discovery of random particle motion using smoke particles colliding with air molecules

The temperature and kinetic energy of the atoms do not change however their electrostatic potential energy increase is significantly

Solids have large electrostatic forces liquids have a smaller electrostatic Force whilst gases have negligible electrostatic forces

The energy required to increase 1kg of a substance by 1 degree Celsius

E=mc0

The energy required to change from solid to liquid phase per unit mass while at a constant temperature

The energy required to change a substance from liquid to gas phase per unit mass while at a constant temperature

energy is equal to the mass of the substance x the specific latent heat.

Energy is also equal to the current x the voltage x the time.

This can then be rearranged so that the specific latent heat is equal to the current x the voltage x the time all divided by the mass

Perfectly elastic collisions

Each atom occupies negligible volume compared to the volume of the gas

each atom move in random directions with random speeds

The pressure in a substance is inversely proportional to its volume

the pressure in a substance is directly proportional to the temperature

pV is equal to NRT where is the molar gas constant and N represents the number of molecules (number of moles x avogadros number)

pV=1/3Nm x (rms)

A graph showing the spread of speeds of particles in a gas where speed of the particle is on the x axis and number of particles with that speed on the y axis

The internal energy of a gas is the sum of the kinetic and potential energies of the particles inside the gas

A force that keeps a body Moving with a uniform speed along a circular path

Oscillating motion for which the acceleration of the object is given by a = - Omega squared x the displacement

When it's released from It's Beginning height the potential energy is maximum and the kinetic energy is minimum as it swings down to the centre point the potential energy becomes minimum and the kinetic energy of a maximum before going out again to its maximum amplitude where the potential energy is maximum and the kinetic energy is minimum

When an external force that acts on an oscillator has the effect of reducing the amplitude of its oscillations

When the driving frequency is equal to the Natural frequency of an oscillating object

MRI scans or magnetic resonance imaging allows for diagnostic scans of our bodies to be obtained without using harmful x-rays

The gravitational force exerted per unit mass on a small object placed at the point within the field

Uniform and radial

Force is directly proportional to the product of the two masses and inversely proportional to the radius squared

F=-GMm/r^2

The orbit of a planet is an ellipse with the sun at one of the two foci

A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time

t squared is directly proportional to r cubed

They must be in orbit above the Earth's equator , they must rotate in the same direction as the Earth's rotation and they must have an orbital period of 24 hours or one day

The velocity required of an object in order to escape the the force of the gravitational field

It begins as a stellar nebula which is a collection of astral dust rocks and gas which forms a protostar if the mass of the star is between 0.5 and 10 solar masses then it will form a red giant which will become a white dwarf and then cool tube to finish off as a black dwarf. if the mass of the store is greater than 10 solar masses then it will become a red super giant which will explode in a supernova and then will become a black hole if the mass of the core is greater than 3 solar masses or a neutron star if the mass of the core is greater than the chandresekhar limit but less than 3 solar masses

if the mass of the store is greater than 10 solar masses then it will become a red super giant which will explode in a supernova and then will become a black hole if the mass of the core is greater than 3 solar masses or a neutron star if the mass of the core is greater than the chandresekhar limit but less than 3 solar masses

if the mass of the store is greater than 10 solar masses then it will become a red super giant which will explode in a supernova and then will become a black hole if the mass of the core is greater than 3 solar masses or a neutron star if the mass of the core is greater than the chandresekhar limit but less than 3 solar masses

Asteroids are objects too small and uneven to be planets whilst comets are small bodies made up of ice dust and small pieces of rock which orbit the sun in elliptical orbits

A diagram showing stars in our galaxy measuring them with their relationship between luminosity on the y-axis and average surface temperature on the x axis

The energy level with the most negative value

External energy is required to remove an electron from the atom

Each element produces a unique emission line because of its unique set of energy

All visible frequencies or wavelength of presents

A series of dark spectral lines against the background of a continuous spectrum showing the wavelength as bright emission spectral lines for the same gas atoms

An idealised object that absorbs all electromagnetic radiation that shines onto it

The maximum wavelength is inversely proportional to the temperature

The total power radiated per unit surface temperature of a black body is directly proportional to the fourth power of the absolute temperature of the black body

The average distance from the Earth to the Sun

The distance travelled by light in a vacuum in a time of one year

A technique used to determine the distance to stars that are relatively close to the Earth at distance is less than 100 parsec

Distance = 1/parallax angle (angle between the earth position and the star)

Whenever a wave source moves relative to an Observer the frequency and wavelength change

When a Galaxy is moving towards the Earth as the wavelength appears shorter

When a Galaxy is moving away from the Earth the wavelength appears stretched

The recessional speed of the galaxy is almost directly proportional to its distance from the Earth (Ho hubble constant v=Ho x d

The universe is homogeneous and isotropic meaning that whatever angle you look at it it is the same and the matter is distributed uniformly across the universe

Scattered faints radiation from the initial big bang explosion

1 over hubble's constant

The charge stored per unit voltage across it measured in farads

When in series the inverse of the capacitance is added together whilst in parallel the base capacitance is added

Stored energy is equal to half QV

Half V squared c

Half Q squared / c

The force experienced per unit positive charge at that point

The magnitude of the electrostatic forces between two point charges is directly proportional to the product of those charges and inversely proportional to the radius between them squared

The work done per unit charge in bringing a positive charge from infinity to that point

When electrons are emitted through heat

A field surrounding a permanent magnet or a current carrying conductor in which magnetic objects experience a force

The thumb is motion the first finger is field and the second finger it is current

The strength of the field

Place two magnets on a balance or weighing scales with a uniform magnetic field between them and a stiff copper wire of known length perpendicular to the magnetic field between them. Connect the section of wire in series with an ammeter and a variable power supply the balance is zero and when there's no current in The Wire a vertical upward Force will be applied which will be equal to the downward force f which can be calculated from the change in mass reading using f = mg. The magnetic flux density can then be calculated using the equation B = f over IL

A device that uses both electric and magnetic fields to select charged particles of specific velocities

The motion of the coil relative in a magnetic field makes electrons move because they experience a magnetic force given by b e v the moving electrons constitute an electrical current within the coil so the process has produced electrical energy

The product of the number of turns in the coil and the magnetic flux measured in Weber turns

The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linkage

The direction of the induced EMF or current is always such as to oppose the change producing it

Increasing the number of turns in the primary or secondary coil in order to increase the voltage or decrease it

A narrow beam of Alpha particles was targeted at a thin piece of gold foil the alpha particles were scattered by the foil and detected on a zinc sulfide screen mounted in front of a microscope and most of the alpha particles passed straight through

All of the positive charge was concentrated in the centre of an atom in a tiny nucleus surrounded by free-floating electrons

An element which has the same number of protons but a different number of neutrons

The force responsible for keeping like charges close to each other in the nucleus

Particles and antiparticles that are affected by the strong nuclear force including protons neutrons and meson. hadrons Decay by the weak nuclear force

Particles and antiparticles that are not affected by the strong nuclear force for example electrons neutrinos and muons

Any hadron made with a combination of three quarks for example protons and neutrons

A particle of negligible mass used to balance charges

A neutron decays into a proton and electron and an anti neutrino

A proton decays into a neutron a positron and, a neutrino

Releasing a 42 helium nucleus

Gamma photons are emitted if a nucleus has surplus energy following alpha or beta emission and the equation stays the same just adding gamma emission

The time taken for the number of active nuclei in a substance to half

The rate of which nuclei Decay measured in becquerels and can be worked out using the equation A = Lambda x N

Measuring the time since organisms died based on comparing the activities or ratios of Carbon 14 to carbon 12 in their nucleus

E equals MC squared

When a particle comes into contact with it antiparticle they destroy each other and their mass is converted into energy and released as gamma ray photons

The minimum energy required to completely separate a nucleus into it's constituent protons and neutrons

Can use Einstein's energy mass equation

The difference between the mass of the completely separated nucleons and the mass of the nucleus

When large molecules break down into smaller molecules releasing energy

When smaller nucleus fuse together forming larger nuclei releasing energy

When a molecule absorbs slow moving neutrons becoming unstable and splitting into two approximately equal halves plus fast neutrons

Slow neutrons used in induced fission because their kinetic energy is similar to the thermal energy of the particles

Used to remove thermal energy produced from the fission reactions

Used to slow down the fast neutrons produced in the fission reactions

Used to absorb excess neutrons so that the reactor does not become unstable

The rate at which the intensity of the x-ray decreases as it passes through matter

The x-ray Photon interacts with an electron within the atom the electron is ejected from the atom but the X-Ray Photon is scattered with reduced energy

An x-ray Photon interacts with the nucleus of the atom it disappears and the electromagnetic energy of the Photon creates an electron and it and a positron

Used to improve the visibility of internal structures in x-ray imaging

A full body Xray whereby a patient is placed on a table which is moved through a 360 degree X-ray machine

CAT scans can create three dimensional images of a patient however they use ionising radiation which can be harmful

Used to detect gamma photons emitted from a medical tracer inside of a patient turning these into images

Thin lead tubes that caused the photons to travel in a uniform Direction

Turns 1 gamma Photon into thousands of photons

Converting photons into electrical impulses that can be sent to the computer

A full body scan used to construct detailed 3D images using gamma radiation

They can help diagnose different types of cancers and help plan complex heart surgeries however the technique is very expensive because of facilities required

When crystal such as quartz are compressed stretched twisted and distorted they producing an electromotive Force

A device use both to generate and receive ultrasound

The simplest type of ultrasound scan where single transducer is used to record along a straight line through a patient

2 dimensional imaging on a screen where the transducer is moved over the patient's skin

The product of the density and the speed of ultrasound in that substance

HL with acoustic impedance similar to the substance used ensures that almost all of the ultrasound enters the patient's body

A technique where you use the reflection of ultrasound from iron rich blood cells to help doctors evaluate blood flow through major arteries

By knowing the original ultrasound frequency the speed of moving blood cells the speed of ultrasound in blood and the angle at which the probe is held to the skin allows us to use the equation.

Use the equation delta f is equal to 2fv cos theta divided by c