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179 Cards in this Set
- Front
- Back
Acceleration |
Rate of change of displacement over time |
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Newton |
The force when a mass of 1kg is accelerated by 1m/s/s |
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Centre of mass |
Where the mass of an object is focused |
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Centre of gravity |
Where the force appears to act |
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Moment / torque of a force |
Force x the perpendicular distance from the pivot |
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Principle of moments |
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 |
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Archimedes principle and state the equation |
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 |
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Work done to a force |
Force x distance moved |
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Principle of conservation of energy |
Total energy in a closed system remains constant, energy can never be created nor destroyed |
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Power |
The rate of work done P=W/t |
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Hookes law |
The extension of a spring is directly proportional to the force exerted on that spring |
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Elastic potential energy equation |
E= half Fx. Its the area under a force extension graph |
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Tensile stress |
Force / cross sectional area |
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Tensile strain |
Extension / original length |
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Young modulus |
Tensile stress / tensile strain |
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Describe briefly how you would determine the young modulus of a wire |
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 |
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Newton's First Law of Motion |
An object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force |
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Newton's Third Law of Motion |
When two objects interact they exert equal and opposite forces on each other |
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Conservation of momentum |
When two objects interact the total momentum in a specified Direction remains constant as long as no external forces act on the system |
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Newton's second law of motion |
The net force acting on an object is directly proportional to the rate of change of its momentum |
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Impulse |
the product of force and time for which this force acts on an object equal to the change in momentum |
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Millikan's experiment |
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 |
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Kirchoff's 1st law |
The sum of the currents in to that point is equal to the sum of the current out of that point |
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1 volt |
1 volt is the potential difference across a component when one joule of energy is transferred per unit charge passing through the component |
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Electromotive Force |
The energy transferred from chemical energy or another form to electrical energy per unit charge |
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the electron gun |
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 |
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Ohm's law |
When internal factors such as temperature remain constant the current in the wire is directly proportional to the potential difference across it |
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A diode |
An electrical component which only allows a current to flow in one particular Direction |
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resistivity |
The resistivity of a material at a given temperature is the product of the resistance and the cross sectional area divided by the length |
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The difference between conductors semiconductors and insulators |
The number density of free moving electrons in conductors is very high semiconductors medium and insulators very low |
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NTC |
Negative temperature coefficient meaning that resistance drops as the temperature increases |
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Light dependent resistor or LDR |
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 |
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Equations for power losses |
P = I^2R P=V^2/R |
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The kilowatt hour |
The energy transferred by a device with power of 1 kilowatt operating for a time of 1 hour |
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Kirchoff's 2nd Law |
The sum of the electromotive forces is equal to the sum of the potential differences around the closed loop |
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The equation for EMF |
E=I(R+r) |
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The equation for potential dividers |
Vout=V in x R1/R1+R2 |
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Progressive waves |
an oscillation that travels through matter transferring energy from one point to another |
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phase difference |
The difference between the displacement of particles along a wave or on different waves |
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Antiphase |
When they have a phase difference of 180 degrees or pi radians |
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refraction |
When a wave changes Direction as it changes speed passing from one medium to another |
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diffraction |
When waves pass through a gap or travel around an obstacle they spread out |
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polarisation |
Particles oscillate along One Direction Only |
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intensity |
The power passing through a surface per unit area |
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The relationship between intensity and amplitude |
Intensity is directly proportional to the amplitude squared |
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What is the range of visible light |
400 to 700 NM |
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Total internal reflection |
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 |
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superposition |
When two waves interact the individual displacements are added |
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constructive interference |
When superposition occurs between two waves with similar displacement |
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Destructive interference |
When two waves interact having opposite displacements |
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path difference |
The difference in distance travelled between two adjacent waves |
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Young's double slit experiment |
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 |
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stationary waves |
Waves which have no net transfer of energy |
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Harmonics of string fixed at both ends |
Wavelength increases from a half wavelength in intervals of half wavelength |
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Harmonics fixed at one end |
Wavelengths starting at a quarter wavelength and increasing of in intervals of half wave lengths |
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Harmonics fixed at no ends |
Wavelength starting at half wavelength increasing in intervals of half wavelengths however there must be an antinode at each end |
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Photon |
A tiny packets of electromagnetic energy |
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The photoelectric effect |
When electromagnetic radiation incident on the surface of a metal causes electrons to be emitted |
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gold leaf electroscope |
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 |
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threshold frequency |
The minimum required frequency of the incident radiation in order for photoelectrons to be emitted |
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What happens when you increase the intensity or frequency of the incident radiation |
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 |
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work function |
The minimum energy required to free an electron from the surface of the metal |
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Wave particle duality |
The idea that all matter can be represented in particle or wave nature |
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The de broglie wavelengths |
The wavelength is directly proportional to the inverse of its momentum and equal to Planck's constant divided by its momentum |
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the triple point |
Given a specific temperature and pressure a substance can exist in all three phases of matter at once |
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temperature |
A measure of the total internal energy of a substance |
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The zeroth law of thermodynamics |
If two objects are in thermal equilibrium with each other and you add a third they are all in thermal equilibrium with each other |
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absolute zero |
-273.15 it is the point at which the internal energy of a substance is 0 |
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the kinetic model |
The arrangement of particles in solids liquids and gases |
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brownian motion |
The discovery of random particle motion using smoke particles colliding with air molecules |
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What happens when a substance changes state or phase |
The temperature and kinetic energy of the atoms do not change however their electrostatic potential energy increase is significantly |
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Which phase has the largest electrostatic potential energy |
Solids have large electrostatic forces liquids have a smaller electrostatic Force whilst gases have negligible electrostatic forces |
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Specific heat capacity |
The energy required to increase 1kg of a substance by 1 degree Celsius |
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The equation for specific heat capacity |
E=mc0 |
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Specific latent heat of fusion |
The energy required to change from solid to liquid phase per unit mass while at a constant temperature |
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Specific latent heat of vaporization |
The energy required to change a substance from liquid to gas phase per unit mass while at a constant temperature |
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The equation for working out the energy using specific latent heat |
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 |
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the assumptions made in the kinetic model for an ideal gas |
Perfectly elastic collisions Each atom occupies negligible volume compared to the volume of the gas each atom move in random directions with random speeds |
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gas laws |
The pressure in a substance is inversely proportional to its volume the pressure in a substance is directly proportional to the temperature |
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state the equations of an ideal gas |
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) |
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The boltzmann distribution |
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 |
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Internal energy in thermal physics |
The internal energy of a gas is the sum of the kinetic and potential energies of the particles inside the gas |
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centripetal Force |
A force that keeps a body Moving with a uniform speed along a circular path |
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Simple harmonic motion |
Oscillating motion for which the acceleration of the object is given by a = - Omega squared x the displacement |
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Explain how the distribution of energy changes as a pendulum swings |
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 |
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damping |
When an external force that acts on an oscillator has the effect of reducing the amplitude of its oscillations |
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resonance and an example |
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 |
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Gravitational field strength |
The gravitational force exerted per unit mass on a small object placed at the point within the field |
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Main two types of gravitational field |
Uniform and radial |
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Newton's law of gravitation |
Force is directly proportional to the product of the two masses and inversely proportional to the radius squared F=-GMm/r^2 |
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Kepler's first law |
The orbit of a planet is an ellipse with the sun at one of the two foci |
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Kepler's second law |
A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time |
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Kepler's third law |
t squared is directly proportional to r cubed |
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Geostationary satellites |
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 |
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Escape velocity |
The velocity required of an object in order to escape the the force of the gravitational field |
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The life cycle of a star |
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 |
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What is the difference between a comet and an asteroid |
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 |
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The hertzsprung-russell diagram |
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 |
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What is the ground state |
The energy level with the most negative value |
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Why are energy levels negative |
External energy is required to remove an electron from the atom |
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Emission line spectra |
Each element produces a unique emission line because of its unique set of energy |
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Continuous spectra |
All visible frequencies or wavelength of presents |
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Absorption line spectra |
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 |
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Black body radiation |
An idealised object that absorbs all electromagnetic radiation that shines onto it |
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Wiens displacement law |
The maximum wavelength is inversely proportional to the temperature |
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Stefan's law |
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 |
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Define one astronomical unit |
The average distance from the Earth to the Sun |
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define the light year |
The distance travelled by light in a vacuum in a time of one year |
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Stellar parallax |
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) |
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the Doppler effect |
Whenever a wave source moves relative to an Observer the frequency and wavelength change |
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Blue shift |
When a Galaxy is moving towards the Earth as the wavelength appears shorter |
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redshift |
When a Galaxy is moving away from the Earth the wavelength appears stretched |
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hubble's law |
The recessional speed of the galaxy is almost directly proportional to its distance from the Earth (Ho hubble constant v=Ho x d |
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the cosmological principle |
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 |
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CMBR or cosmic microwave background radiation |
Scattered faints radiation from the initial big bang explosion |
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How can you determine the age of the universe |
1 over hubble's constant |
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capacitance |
The charge stored per unit voltage across it measured in farads |
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How are capacitors connected |
When in series the inverse of the capacitance is added together whilst in parallel the base capacitance is added |
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How do you work out the stored energy in a capacitor |
Stored energy is equal to half QV Half V squared c Half Q squared / c |
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electric field strength |
The force experienced per unit positive charge at that point |
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Coulomb's Law |
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 |
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electric potential |
The work done per unit charge in bringing a positive charge from infinity to that point |
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thermionic emission |
When electrons are emitted through heat |
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magnetic field |
A field surrounding a permanent magnet or a current carrying conductor in which magnetic objects experience a force |
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Flemings left hand rule |
The thumb is motion the first finger is field and the second finger it is current |
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Magnetic flux density |
The strength of the field |
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How to determine magnetic flux density of the magnets |
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 |
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velocity selector |
A device that uses both electric and magnetic fields to select charged particles of specific velocities |
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Electromagnetic induction |
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 |
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magnetic flux linkage |
The product of the number of turns in the coil and the magnetic flux measured in Weber turns |
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Faraday's law |
The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linkage |
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lenz's law |
The direction of the induced EMF or current is always such as to oppose the change producing it |
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Step up and step down Transformers |
Increasing the number of turns in the primary or secondary coil in order to increase the voltage or decrease it |
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Rutherford's alpha scattering experiment |
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 |
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the nuclear model |
All of the positive charge was concentrated in the centre of an atom in a tiny nucleus surrounded by free-floating electrons |
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isotope |
An element which has the same number of protons but a different number of neutrons |
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The strong nuclear force |
The force responsible for keeping like charges close to each other in the nucleus |
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hadrons |
Particles and antiparticles that are affected by the strong nuclear force including protons neutrons and meson. hadrons Decay by the weak nuclear force |
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Leptons |
Particles and antiparticles that are not affected by the strong nuclear force for example electrons neutrinos and muons |
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Baryons |
Any hadron made with a combination of three quarks for example protons and neutrons |
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Neutrinos |
A particle of negligible mass used to balance charges |
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Beta minus Decay |
A neutron decays into a proton and electron and an anti neutrino |
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beta plus Decay |
A proton decays into a neutron a positron and, a neutrino |
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alpha decay |
Releasing a 42 helium nucleus |
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gamma Decay |
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 |
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half-life |
The time taken for the number of active nuclei in a substance to half |
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Activity of a substance and state its formula |
The rate of which nuclei Decay measured in becquerels and can be worked out using the equation A = Lambda x N |
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carbon dating |
Measuring the time since organisms died based on comparing the activities or ratios of Carbon 14 to carbon 12 in their nucleus |
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Einstein's energy mass equation |
E equals MC squared |
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What is particle annihilation |
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 |
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binding energy |
The minimum energy required to completely separate a nucleus into it's constituent protons and neutrons Can use Einstein's energy mass equation |
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Mass defect |
The difference between the mass of the completely separated nucleons and the mass of the nucleus |
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nuclear fission |
When large molecules break down into smaller molecules releasing energy |
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nuclear fusion |
When smaller nucleus fuse together forming larger nuclei releasing energy |
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induced fission |
When a molecule absorbs slow moving neutrons becoming unstable and splitting into two approximately equal halves plus fast neutrons |
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thermal neutron |
Slow neutrons used in induced fission because their kinetic energy is similar to the thermal energy of the particles |
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nuclear coolant |
Used to remove thermal energy produced from the fission reactions |
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nuclear moderator |
Used to slow down the fast neutrons produced in the fission reactions |
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nuclear control rods |
Used to absorb excess neutrons so that the reactor does not become unstable |
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Attenuation of X-rays |
The rate at which the intensity of the x-ray decreases as it passes through matter |
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Compton scattering |
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 |
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Pair production |
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 |
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Contrast medium |
Used to improve the visibility of internal structures in x-ray imaging |
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CAT scans |
A full body Xray whereby a patient is placed on a table which is moved through a 360 degree X-ray machine |
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One advantage and one disadvantage of CAT scans |
CAT scans can create three dimensional images of a patient however they use ionising radiation which can be harmful |
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the gamma camera |
Used to detect gamma photons emitted from a medical tracer inside of a patient turning these into images |
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The collimator in a gamma camera |
Thin lead tubes that caused the photons to travel in a uniform Direction |
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Scintillator in a gamma camera |
Turns 1 gamma Photon into thousands of photons |
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Photomultiplier tubes in a gamma camera |
Converting photons into electrical impulses that can be sent to the computer |
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pet scans |
A full body scan used to construct detailed 3D images using gamma radiation |
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One advantage and one disadvantage of pet scans |
They can help diagnose different types of cancers and help plan complex heart surgeries however the technique is very expensive because of facilities required |
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the piezoelectric effect |
When crystal such as quartz are compressed stretched twisted and distorted they producing an electromotive Force |
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An ultrasound transducer |
A device use both to generate and receive ultrasound |
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A scan |
The simplest type of ultrasound scan where single transducer is used to record along a straight line through a patient |
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B scan |
2 dimensional imaging on a screen where the transducer is moved over the patient's skin |
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acoustic impedance |
The product of the density and the speed of ultrasound in that substance |
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coupling gel |
HL with acoustic impedance similar to the substance used ensures that almost all of the ultrasound enters the patient's body |
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Doppler ultrasound |
A technique where you use the reflection of ultrasound from iron rich blood cells to help doctors evaluate blood flow through major arteries |
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How to determine the speed of blood |
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 |