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143 Cards in this Set
- Front
- Back
State the 2 laws of reflection of light |
-The incident ray, normal at the point of incidence and the reflected ray all lie on the same plane -Angle of incidence = angle of reflection |
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Define 'parallax' |
The apparent movement of one object relative to another due to the motion of the observer |
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Define 'Virtual Image' |
an image formed by the apparent intersection of rays
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Define 'magnification' |
the ratio of the image height to the object height |
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State both laws of refraction of light |
-the normal, incidence and reflected ray all lie on the same plane
-the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant |
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Define 'refractive index of a medium' |
the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from a vacuum into that medium |
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Define 'critical angle' |
when light travels from a denser to a rarer medium and the angle of incidence whose corresponding angle of refraction on 90 degrees |
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Define 'total internal reflection' |
when light going from a denser to a rarer medium strikes the second medium at an angle of incidence greater than the critical angle so is therefore reflected back into the first media |
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Define 'speed' |
rate of change of distance with respect to time |
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Define 'displacement' |
distance in a given direction |
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define 'velocity' |
rate of change in displacement with respect to time |
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Define 'acceleration' |
rate of change in velocity with respect to time |
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Define 'scalar quantity' |
a quantity which has only magnitude (no direction) |
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Define 'vector quantity' |
a quantity which has both magnitude and direction in space |
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Define 'vector components' |
expressing a vector in terms of 2 other vectors so that it's the resultant of these 2 |
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Define 'perpendicular components' |
resolving a vector into components which are right-angles to each other |
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Define 'force' |
anything that causes a body to change (its velocity) |
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Define 'mass' |
a measure of how difficult it is to accelerate that body |
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Define 'Newton' |
1N is the force that gives a mass of 1Kg an acceleration of 1m/s |
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Define 'weight' |
the force of an object due to gravity acting on it |
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State Newton's 1st law of motion |
every body will remain in a state of rest/travel at a constant velocity unless an (unbalanced) external force acts on it |
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State Newton's 2nd law of motion |
when an unbalanced force acts on a body, the rate of change in the body's momentum is directly proportional to the force and takes place in the direction of the force |
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State Newton's 3rd law of motion |
If body A exerts a force on body B, then body B exerts an equal but opposite force on body A |
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State the principal of conservation of momentum |
in the interaction between 2+ bodies, the total momentum of the bodies before and after the interaction is the same (as long as no external force acts on the bodies) |
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Define 'Density' |
mass per unit volume |
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Define 'pressure' |
force per unit area |
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State 'archimedes' principal' |
when an object is partially/fully immersed in a fluid it experiences an upthrust equal in magnitude to the weight of the fluid displaced |
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State the law of flotation |
weight of floating body = weight of fluid it displaces |
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State Boyle's law |
at a constant temperature the volume of a fixed mass of gss is inversely proportional to its pressure |
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Give the conditions needed for eqilibrium |
-vector sum of forces in any direction = 0 -sum of moments about any point = 0 |
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Define 'couple' |
two parallel forces with the same magnitude acting in opposite directions |
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Define 'joule' |
1J of work is done when a force of 1N acts for a distance of 1m in the direction of the force |
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Define 'energy' |
the ability to do work |
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State the principal of conservation of energy |
energy can't be created/destroyed, only converted form one form to another |
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Define 'kinetic energy' |
the energy a body has due to its motion |
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Define 'potential energy' |
the energy a body has due to its position ina force field |
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Define 'power' |
-the rate at which work is done
-the rate at which energy is converted from one form to another |
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Define 'temperature' |
the measure of the hotness/coldness of a body |
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Define 'thermometric property' |
any physical property that changes measurably with temperature |
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Define 'heat capacity of an object' |
heat energy needed to change its temperature by 1 K |
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Define 'specific heat capacity of a body' |
heat energy needed to change the temperature of 1Kg of that substance by 1K |
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Define 'latent heat' |
heat energy needed to change a body's state without a change in temperature |
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Define 'specific latent heat' |
heat enery needed to change the state of 1Kg of a substance without a change in temperature |
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Define 'specific latent heat of fusion' |
ammount of heat energy needed to change the state of 1Kg of a substance from solid to liquid without a change in temperature |
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Define 'specific latent head of vaporisation' |
heat of energy needed to change the state of 1Kg of a substance from liquid to gas without a change in temperature |
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Define 'conduction' |
movement of heat energy through a substance by the passing on of molecular vibration without an overall motion of the substance |
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Define 'U-value of a structure' |
heat energy conducted per second through 1m squared of that structure when there's a temperature difference of 1K between its ends |
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Define 'radiation' |
transfer of heat energy from one place to another in the form of electromagnetic waves |
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Define 'solar constant/irradiance' |
average amount of sun's energy falling per second perpendicularly on 1m squared of the earth's atmosphere |
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Define 'convection' |
transfer of heat through a fluid by means of circulating currents of a fluid caused by the heat |
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define "travelling mechanical wave" |
a disturbance carrying energy through a medium without any overall motion of that medium |
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define "travelling wave" |
a disturbance travelling out from its source which transfers energy to other bodies it passes through |
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define "transverse wave" |
a wave where the direction of vibration is perpendicular to the direction the wave is travelling |
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define "longitudinal wave" |
a wave where the direction of vibration is parallel to the direction the wave is travelling |
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define "amplitude" |
the maximum distance of any particle from its undisturbed position (maximum height of vibration) |
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define "crest" |
top of the wave |
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define "trough" |
bottom of the wave |
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define "oscilltion/cycle of a wave" |
the disturbance produced by one complete vibration of the source (1 crest + 1 trough) |
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define "wavelength" |
distance between 2 corresponding points between to cycles of waves |
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define "frequency" |
number of cycles passing any point per second |
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define "velocity of a wave" |
distance travelled by 1 cycle in 1 second |
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define "wave reflection" |
bouncing of waves off of an obstacle in their path |
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define "wave refraction" |
changing of direction of a wave when it enters a region where its speed changes (medium) |
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define "wave diffraction" |
sideways spreading of waves into a region beyond a gap/obstacle
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define "wave interference" |
when waves from 2 sources meet and a new wave is produced and the amplitude of the new wave is the sum of the amplitudes of the 2 original waves |
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define "constructive interference" |
when waves from 2 sources meet and the resultant amplitude is greater than the amplitudes of the original waves |
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define "destructive interference" |
when waves from 2 sources meet and the resultant amplitude is less than the amplitudes of the original waves |
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define "coherent sources" |
when 2 sources produce waves which are in phase with eachother/which have a constant phase difference between them. These waves have equal frequency |
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define "interference pattern" |
the wave pattern formed when waves from 2+ coherent sources meet |
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define "stationary waves" |
the resulting wave of when 2 periodic travelling waves of equal frequency+amplitude which move in opposite directions meet + interfere with eachother. |
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define "doppler effect" |
the apparent change in frequency of waves due to the motion of the source/observer |
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define "overtones" |
frequencies that are multiples of a certain frequency (ie f, 2f, 3f etc)
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what dictates a sound's "loudness" |
amplitude |
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what dictates a sound's "pitch" |
frequency |
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what dictates a sound's "quality" |
number of overtones + relative strengths of the different overtones |
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define "frequency limits of audibility" |
highest and lowest frequency which can be heard by humans |
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define "natural frequency of vibration" |
the frequency at which on object, which is free to vibrate, is most likely to vibrate at
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define "resonance" |
-when the frequency of a periodic force applied to a body is the same as/near to its natural frequency, that body will vibrate with a large amplitude |
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define "fundamental frequency" |
a string vibrating with an antinode at the center and a node an each end (ie no other nodes/antinodes present) |
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define "harmonics" |
Frequencies which are multiples of an object's fundamental frequency |
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define "polarisation" |
controlling the direction in which an electromagnetic wave is vibrating |
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define "dispersion" |
the separation of the different wavelengths present in light |
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define "insulator" |
a substance an electric charge can't flow through |
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define "conductor" |
a substance an electric charge can flow through |
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define "electric field" |
any region of space where a static charge experiences a force other than gravity |
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define "potential difference" |
-the P.D between 2 points in an electric field is the work done on bringing a charge of 1C from one point to another
-the P.D between 2 points in a circuit is the energy lost by 1C as it moves from A to B |
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define "the Volt" |
the P.D between 2 points is 1 volt if 1 joule of work is done when 1 coulomb is brought from A to B |
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define "potential at a point" |
the P.D between a point and the earth |
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define "current" |
the flow of electrons |
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what is "electromotive force" |
applied P.D in a circuit to maintain an electric field in the circuit |
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what is "electrolysis" |
when a current passes through a liquid/paste and creates a chemical reaction |
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what is an "electrolyte" |
Liquid in which electrolysis occurs in |
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what is an "electrode" |
rods/plates dipped into the electrolyte |
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what is an "anode" |
an electrode connected to the positive terminal of the power supply |
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what is a "cathode" |
an electrode connected to the positive terminal of the power supply |
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what is a "voltameter" |
the container electrodes + electrolytes are in |
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what are "inactive electrodes" |
electrodes which don't take part in the chemical reaction |
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what are "active electrodes" |
electrodes which do take part in the chemical reaction |
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define "Ion" |
an atom/molecule that has lost/gained 1+ electrons |
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what is the "kilowatt-hour" |
amount of energy used by a 1000W appliance in one hour |
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define "semiconductor" |
-a substance whose resistivity is between that of a good conductor and a good insulator -a substance whose resistance decreases with increasing temperature
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what are "valence electrons" |
electrons on the outer shell of an atom |
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what is a "positive hole" |
the space remaining when an electron breaks free from a covalent bond |
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what is a "conduction electron" |
an electron which has gained enough thermal energy to break free from a covalent bond |
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define "intrinsic conduction" |
the conduction in a pure semiconductor due to electrons moving from '-' to '+' and an equal number of positive holes moving the opposite direction |
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define "doping" |
the adding of impurities to a semiconductor to increase its conductivity |
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define "N-type conductor" |
a semiconductor in which the impurity added produces more conduction electrons |
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define "P-type conductor" |
a semiconductor in which the impurity added produces more positive holes for conduction |
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define "extrinsic conduction" |
increased conduction in a semiconductor due to the addition of impurities |
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define "P-N junction" |
a semiconductor which is partly doped N-type and the rest doped P-type |
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define "depletion layer" |
the region in a P-N junction in which there are no free majority charge carriers and behaves as an insulator |
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define "junction voltage" |
the P.D that exists across a P-N junction caused by holes and electrons moving across the junction when it was formed |
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define "forward-biased junction" |
a circuit in which the diode allows current to flow |
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define "reverse-biased junction" |
a circuit in which the diode doesn't allow current to flow |
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define "retrification" |
converting D.C to A.C |
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define "magnetic flux density (B)" |
B at a point in a magnetic field, is a vector whose magnitude is the force (F) that would be experienced by a conductor of length (L) 1m carrying 1A at right-angles to the field at that point and whose direction is the direction of the force on a north pole placed at that point
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define the "ampere" |
it's a constant current which, if maintained in 2 straight parallel conductors of infinite length of negligible cross section and placed 1m apart in a vacuum, would produce a force on each conductor of 2x10-7 per meter of length |
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define "electromagnetic induction" |
the phenomenon which occurs when the magnetic field passing through a coil changes and an EMF appears in the coil |
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define "magnetic flux" |
Ammount of magnetic force passing though an area
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define "weber" |
if the magnetic flux density over an area of one meter squared is one tesla then the flux through the area is 1 weber
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state Faraday's law of electromagnetic induction |
the size of the induced EMF is directly proportional to the rate of change of flux
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state Lenz's law |
the direction of an induced current is always such as to oppose the change producing it |
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define "Mutual induction" |
there is said to be mutual induction between 2 coils if a changing magnetic field in one coil causes an induced EMF to appear in a nearby coil |
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`define "self induction" |
whenever the current passing through a coil changes, the coil's surrounding magnetic field changes. This changing field induces an EMF in the coil that opposes the changing current |
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define "thermionic emission"
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the giving off of electrons from the surface of a hot metal
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define "cathode rays"
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streams of high-speed electrons moving from a cathode
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define "the electron-volt"
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the amount of energy gained or lost by an electron when it moves through a potential difference of 1 volt
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state the "photoelectric effect"
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the emission of electrons from the surface of a metal by electromagnetic radiation of a suitable frequency
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what is a "photocell"
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a device which conducts current when light of a suitable frequency shines on it
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what is the "threshold frequency" for a given metal
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the frequency below which photo emission won't occur
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define "work function"
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the minimum energy needed to remove the loosest electron from the surface of a metal
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state Einstein's Photoelectric Law
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the maximum energy of an electron is
HF - WORK FUNCTION (H=Planck's constant and F= frequency of the incident radiation) |
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define "X-Rays"
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electromagnetic radiation of high frequency produced when cathode rays (rays of electrons) strike a metal target with a high melting point
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what is an "emission spectra"
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when light from a luminous source undergoes dispersion, this is the resulting pattern
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What does "Laser" stand for
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Light Amplification by Stimulated Emission of Radiation
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what is an "isotope"
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atoms of an element that have the same number of protons but a different number of neutrons
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define "radioactivity"
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the disintegration of decay of the nuclei of certain atoms with the emission of one or more types of radiation
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what is the "activity" of a radioactive substance
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the number of nuclei of that substance decaying per second
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state the "law of radioactive decay"
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the number of nuclei decaying per second (ie activity) is directly proportional to the number of nuclei undecayed
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what is the "half life" of a radioactive isotope
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-the time taken for half of the undecayed atoms to undergo decay
-the time taken for its activity to be decreased by half |
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define "nuclear fission"
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the splitting up of a large nucleus into two smaller nuclei of roughly the same size
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define "critical size"
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the size of the sample in which a chain reaction can occur
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define "nuclear fusion"
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the joining of two small nuclei to form a large nucleus
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