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### absolute zero

the extrapolated temperature at which the pressure and volume of an ideal gas are predicted to be zero; the temperature at which the molecules have no random kinetic energy.

### absorption spectra

When a continuous spectrum of light is shone through and element in gaseous form, specific frequencies are preferentially absorbed. the resulting spectrum (with some frequencies missing) is know as the element's ...

### albedo

Some of the radiation received by a planet is relected back into space. The _____ of a sruface is the fration of the power that is scattered (reflected) from the surface compared to total incident power received. It's a ratio and has no units.

### alpha particles

helium nuclei (two protons and two neutrons) emitted as a result of a decaying unstable nucleus.

### angular velocity

when an object is undergoing uniform circular motion at constant speed, _____ is the rate of change of angle (as measured between the radius from the center of the circle to the object and one of the axis).

### artificial (induced ) transmutation

can take place when a nucleus is bombarded by a nucleon, and alpha particle, or other small nucleus. The target nucleus first captures the incoming object and then an emission or decay takes place.

### average (speed, velocity, acceleration)

the steady (constant) value that would have given the same result

### Bainbridge mass spectrometer

_____ allows the isotopic content of a sample to be measured. ions of the same velocity but different mass will follow different circular pathts when moving in a constant perpendicular magnetic field.

### beta - decay

the emission of a fast-moving electron when a neutron decays into a proton, beta particle (negative), and an anitneutrino

### beta + decay

the emission of a fast-moving positive electron (positron) when a proton decays into a neutron, a beta (positive) particle, and a neutrino

### beta particles

fast moving electrons or positrons that have been emitted as a result of a decaying unstable nucleus

### binding energy

the amount of energy that is released when a nucleus is assmebled form its component nucleons. It's also the amount of energy that needs to be added in order to separated in nucleus into its individual nuleons.

### binding energy per nucleon

the total binding energy for a particular nucleus divided by the number of nucleons contained in the nucleus; _____ represents a nucleus that is more energetically stable.

### black-body radiation

At a given temperature, different surfaces will radiate different amounts of EM radiation. The maximum theoretical amount that can be emitted from any surface is known as _____.

### boiling

the process by which molecules of a liquid spontaneous change from the liquid phase into the gas phase throughout the body of the liquid

### carbon dioxide storage and capture

Carbon dioxide is emitetd by fossil fuel power stations. A traditional power station just releases it into the environment, potentially increasing the enhanced greenhouse effect. _____ is the general term for preventing its release into the environment.

### charge-coupled devices (CCDs)

used for image capture across a large range of the EM spectum; examples are digital cameras, video cameras, telescopes, and medical X-ray imaging

### charged particle scattering experiments

on the atomic scale, charged particles can be scattered by nuclei as a result of the Coulumb repulsion between the charge particle and the nucleus. Energy conservation can be used to determine the closest approach distances and thus estimate the upper limit for the size of a nucleus.

### coefficient of volume expansion

the fractional change in volume per degree change in temperature; units are 1/K

### combined heating and power systems (CHP)

improve the overall efficiency of electricity generation by utilizing the thermal energy generated to, for example, supply hot water for local domestic supply

### components of vecotrs

When a vector is resolved into different direcions, the results are called _____.

### compressions

the points on a longitudinal wave where all the particles are 'bunched together' (high pressure)

### law of conservation of charge

the total charge of an isolated system of interacting particles always remains the same

### law of conservation of linear momentum

the total linear momentum of a system of interacting particles remains constant provided there is not resultant external force (the system is isolated)

### constructive interference

When two identical waves meet at point and the waves are exactly in phase, the resulting wave has twice the amplitude of either of the original waves

### control rods

movable rods that readily absorb neutrons; they can be introduced or removed from the reaction chamber in order to control the chain reaction

### controlled nuclear fission

takes place in power stations; excess neutrons are absored to ensure that the nuclear reactions take place at a constant rate

### correlation and cause

two measurements are _____ if there is a statistical/mathematical link between the measurements; two measurements are said to have a casual link if one measurement is related to a factor that causes a change in the second measurement. The fact that two measurements are correlated does not imply that here is a causal link between the two.

### Coulomb's law

the electrostatic force between any two point charges masses is proportional the product of the charges and inversely proportional to the square of their distance of separation

### centripital acceleration (CPA)

the acceleration of an object moving at constant speed in uniform circular motion. Even though the speed is constant, the direction of the object's velocity is changing all the time, so the object must be accelerating. The resultant force is called _____. Always directed toward the center of the circle.

### principle of conservation of energy

energy cannot be created or destroyed; it just changes from one type of energy to another

### damping

involves a force that is always in the opposite direction to the direction of motion of the oscillating particle and is a dissipative force (the oscillating particle particle loses energy)

### de Broglie equation

all moving particles have a 'matter wave' associated with them; same equation can be used to calculate the momentum associated with photons

### degraded energy

In any process that involves energy transformations, the energy that is transferred to the surroundings (thermal energy) is no longer available to perform useful work. This unavailable energy is known as _____.

### destructive interference

When two identical waves meet at a point and the waves are exactly (180 degrees) out of phase, the resulting wave has zero amplitude; the two waves cancel each other out

### diffraction

the phenomenon of the spreading of a wave after an aperture or obstacle; the process by which wave energy is received in the geometric shadow region after an obstacle or gap; to be noticeable, whte size of the obstacle or gap needs to be the same order of magnitude as the wavelengh; the spreading of sound around corners or the bending of water waves around a harbour wall

### diffraction equation for angle of first minimum at a circular aperture

1.22 x wavelength divided by slit width in meters

### diffraction equation for angle of first minimum at a single slit

angle equals wavelength divided by slit width

### direction of the force on a current in a magnetic field

perpendicular to the plane that contains the current and the magnetic field; if the current is in the x direction and the magnetic field is in the y direction of a standard graph plotted on a piece of paper, then the force will be out of the paper, in the z direction, as described by Flemming's left-hand rule

### direction of the force on a moving charge in a magnetic field

perpendicular to the plane that contains the direction vector of the charge and the magnetic field. If the charge is moving in the x direction, and teh magnetic field is in the y direction of a standard graph plotted on a piece of paper, then fthe force will be our of the paper, in the z direciton, as described by flemming's left-hand rule.

### direction of magnetic field

the direciton of th force that would be felt by the north pole of a small test magnet if placed at that point

### Doppler approximation for EM waves

the change in frequency of EM waves as a result of the relative motion between source and observer is given by the following approximation

### Doppler effect

a change in frequency of a wave that results from either a moving source of waves, a moving observer, or both.

### Doppler effect with a moving source

observed frequency of sound equals frequency of sound measured when there is no relative motion x (speed of sound in still air + speed of observer divided by speed of sound in air)

### efficiency

the ratio of useful energy to the total energy transferred, often expressed as a percentage; the ratio of useful power out to toal power in; scalar quantity without units

### Eintens equation

plank's constant x frequency of incident EM = work function fo surface in J + maximum kinetic of the emitted photoelectrons

### Einstein's mass-energy equivalence relationship

allows us to calculate the energy that is in the form of mass; energy = mass x the square of teh speed of light

### elastic collisions

collitions in which no energyis gained or lost; collisions between atoms and molecules

### electric field strength

the force per unit charge on a test point charge placed at a point; a vector quantity

### electric potential

the difference in electrical energy per unit test charge at that point; electrical energy per unit test charge at that point; the zero of it is taken to be at infinity so it is equal to the work done per unit charge in bringing a small point test charge from infinity to that point; scalar quantity

### electric power dissipation

a device that is the pboduct of the potential difference across it and the current flowing through it

### 'electron in a box' model

pictures an eletron as being confined to a fixed region in one dimension-the size of a box; Analyses of possible standing-wave patterns for the electron's wavefunction result in only descrete energy levels being available

### electronvolt

unit of energy used on the atomic scale; the energy gained or lost by one electron as it moves throught a potential difference of 1 volt

### emission spectra

When an element is hot enough (given enough energy) it emits light. Analysis of this light shows taht eah element emits specific frequencies; these specific frequencies form the electron's _____.

### emissivity

the ratio of power radiated per unit area by a given surface to the power radiated per unit area by a black body at the same temperature; has no units

### energy balance climate model

If the incoming radiation intensity to a planet's surface and its outgoing radiation intensity are not equal, then the planet's temperature will vary as given by temperature change = (incoming radiation - outgoing radiation) x time taken all divided by the surface heat capacity

### enhanced greenhouse effect

greenhouse effect caused by human activites; possible effect is a rise in sea level; efforts to reduce are Intergovernmental Panel on Climate Change (IPCC), the Kyoto protocol (amendment to UN Framework Convention of Climate Change) and teh Asia-Pacific Partnership on Clean Delelopment and Climate (APPCDC)

### equipotential surfaces and electrical field lines

electric field lines are always at right angles to equipotential surfaces

### expotential surfaces and gravitational field lines

gravitational field lines are always at right angles to equipotential surfaces

### error bar

indicates the absolute uncertainty associalted with a point being plotted on a graph; can be in x or y direction or both

### escape speed from a planet

the speed that an object needs to have at the surgace of the planet in order to have enough kinetic energy to excape the gravitational attraction of teh planet

### evaporation

the process by which induvidual molecules (the faster-moving ones) leave the surface of a liquid and enter the gas pahse; only takes place at teh surface of the liquid at room temperature below the liquid's boiling point

### Faraday's law

the magnitude of an induced e.m.f. is proportional to teh rae of change of flux linkage

### Lenz's law

the direction of teh induced e.m.f is such that if an induced current were able to flow, it would oppose the change which caused it

### first law of thermodynamics (principle of energy conservation)

the energy transferred to the gas from its surroundings equals the increase in the internal energy of the gas + the work done by the gas (in joules)

### forced oscillations

It is possible to force a system to oscillate at any frequency by subjecting it to a changing force at that frequency

### fuel enrichment

the process by which the isotopic composition of a nuclear fuel is increased to make nuclear fissions more likely; usually unranium fuel rods are _____that the percentage of uranium-235 is increased

### gamma radiation

photons of high-energy electromagnetic radiation emitted as a result of a nucleus changing from an excited state into a lower energy state

### gravitational field strength

the force per unit mass on a test point mass placed at that location; a vector quantity

### gravitational field strength vs. gravitational potential energy

gravitational field strenght = the difference in gravitational potential x the distance over which the difference in gravitational potential has been measured

### gravitational potential difference

the difference in gravitational energy per unit test mass between the points

### gravitational potential

gravitational energy per unit test mass at that point; the zero of _____ is taken to be at infinigy so gravitational potential is equal to the work done per unit mass in bringing a small point test point from infinity to that point; a scalar quantity

### formula for gravitational potential due to a point mass

gravitational potentail at a fixed difference = -(universal gravitational constant x mass causing the gravitational potential)/(fixed distance away from the mass)

### gravitational potential energy

the energy that a body has as a result of its position in a gravitational field; a scalar quantity

### greenhouse effect

The atmosphere is transparent to many frequencies of electromagnetic radiation. Much of the power received from the Sun is in the visible and ultraviolet regions. This causes the surface of the Earth to warm up and radiate in the infrared. Some of this infrared radiation is absorbed by gases in the atmosphere, causing the atmosphere to warm up, and re-radiated in all directions; the net effect is that the atmosphere and the surface of the Earth are warmed.

### greenhouse gas

gases in the atmosphere that absorb infrared radiation radiated from Earth; include methane, water vapor, carbon dioxide, and nitrous oxide; also ozone and chorofluorocarbons

### heat exchanger

allows the nuclear reaction to toccur in a place that is sealed off from the rest of the environment; the reactions increase the temerature in the core; this thermal energy is trnasferred to heat water, and the steam that is produced turns the turbines

### hybrid vehicles

uses electric motors with a petrol engine as back-up to provide additional power when necessary; sophisicated computerized wtstems switch from the electric motor to the petrol engine and back as required

### ideal ammeter

has zero resistance; connected in series at the point where the current needs to be measured

### ideal gas

a gas where newton's laws apply to molecular behaviour, there are no intermolecular forces (except in collisions), molecules ar treated as points; molecules are in random motion; the collisions between the molecules are elastic; no time spent in collisions; cannot be liquified

### real gases

show deviations from the equation of state for ideal gases; can approximate to ideal gas behaviour at low pressures

### ideal transformer (step-up and step-down)

changes the voltage of an alternating current (AC) input without any loss of energy. If the output voltage (on the secondary) is greater than the input voltage (on the primary), it is known as a step-up transformer. If the output energy (on the secondary) is less that the input voltage (on the primary), it's a step-down transformer.

### ideal voltmeter

has infinite resistance; connected in parallel between the two points where the potential difference needs to be measured

### impulse

the product ot the resultant force acting on the object and the time for which this force acts; equatl to change of momentum of the object; vector quantity

### induction

happens in e.m.f. whenever there is a relative motions between the conductor and a magnetic field (whenever magnetic lines of flux are cut; takes place whenever there is a time-changing magnetic flux passing through a coil of wire

### inelastic collisions

collisions in which the objects involved in the collision lose energy; all lab. collisions

### intensity

the power per unit area that is received by the observer; related to amplitude of the wave; intensity=power received/area

### internal resistance of a battery

the effective extar resistance that is added to a circuit by the battery

### isotopes

nuclides that contain the same number of protons (so the same element) but different number of neutrons

### Kelvin scale of temperature

has the same unit step as the Celsius temperature scale, but the zero of the _____ is at absolute zero

### Kepler's third law

the cube of the average radius of orbit of a planet is proportional to the square of that planet's orbital time period

### least-significant bit

the bit representing 2^0 and is the furthest on the right when the binary number is written down

### light dependent resistors (LDR)

a device whose resistance depends on the amount of light shining on its surface; an increase in light causes a decrease in resistance

### longitudinal waves

involve oscillations that are in the same directon as the direction of energy transfer; sound waves are an example

### magnetic flux

the magnetic field strength x the area under consideration x the angle between the magnetic field and the normal to the surface

### Malus' law

intensity of the transmitted light = intensity of the incident light x cos^2 of the angle between the plane of vibration and the analyser's preferred direction

### mass deflect

the mass of any nucleus is less than the mass of the component nucleons that go to make it up. The difference between the mass of a nucleus and the masses of its component nucleons is called the mass deflect

### moderator

in a nuclear reactor, it is there to slow down emitted neutrons; collisons between the fast-moving neutrons and the nuclei of the moderator slow them down and allow further nuclear reactions to take place

### molar mass

the mass of one mole of a substance; if an element has a certain mass number, A, then the _____ will be A grams

### mole

the basic SI unit for amount of substance; equal to the amount of that substance that contains the same number of atoms as 0.012 kilograms of Carbon-12

### most-significant bit

the bit representing the highest power of 2 and is the furthest on the left when the binary number is written down

### natural frequency

If a system is temporarily displaced from its equilibrium position, it will oscillate at its _____ of vibration

### existence of neutrino

the energy spectra in beta decay (the beta particles are observed to have a range of possible energies). The _____ was postulated to account for these spectra. The hypothesis being that in addition to the observed beta particles there was another unobserved particle that was sharing the energy on the decay with the beta particle

### Newton's first law

an object continues in uniform motion in a straight line or at rest unless a resultant external force acts (no resultant force = no acceleration

### Newton's second law

the rate of change of momentum of a body is proportional to the resultant force acting on the body; force = mass x acceleration; the direction of the acceleration is equl to the direction of the resultant forece; the direction of the change of momentum is equal to the direction of the resultant force.

### Newton's third law

when two bodies, A and B, interact, the force that A exerts on B is equal and opposite to the force that B exerts on A; these two forces are the same type of force but act on different objects; for every action there is an equal and opposite reaction

### Newton's universal law of gravitation

gravitational attraction between any two poin masses is proportional to the product fo the masses and inversely proportional to the square of their distance of separation

### non-Ohmic conductor

conductors that do not obey Ohm's law; the graph of potential difference vs. current is not a straight line

### nuclear fission

a nuclear reaction in which large luclei are induced to break up into smaller nuclei and release energy in the process

### nuclear fusion

a nuclear reaction in which small nuclei are induced to join together into larger nuclei and energy is released in the process; the main source of the Sun's energy

### nuclear model

consists of a tiny central nulceus containing all the mass and all the positive charge; nulceus is made up of protons and neutrons; negative electrons are kept in orbit around the nucleus as a result of the electrostatic attration between the electrons and the nucleus

### nuclide

the name given to a particular species of atom-one whose nucleus contains a specific number of protons and neutrons

### ohmic conductor

conductors that obey Ohm's law for a wide range of potential difference and currents; the graph of potential difference vs. current is a straight line through the orgin

### Ohm's law

the current flowing through a piece of metal is proportional to the potential difference across it, provided the temperature remains constant

### optically active substance

a substance that rotates the plane of polarization of light that passes through it

### orbital motion

the gravitational attraction between the satellite and the mass that provides the centripetal force for circular motion when a satellite is in orbit around a mass

### oscillating water column ocean-wave converter

uses the kinetic energy of waves to generate electrical energy

### path difference

Interferecne often takes place at a given point in space as a result of there being two different routes for the wave energy to travel from source to that point; the _____ is the difference in the total lengths of teh two routes; often expressed in terms of the wavelength of the wave

### percentage uncertainty

the ratio between the absolute uncertainty and the recorded value expressed as a percentage

### period

the time taken for one complete oscillation; the time taken for one complete wave to pass any given point; measured in seconds

### phase difference

a measure of how "in step" different particles are; in phase = moving together; out of phase = half a cycle off

### photoelectric effect

the phenomena by which electrons are emitted from the surface of some metals when the surface is illuminated with electromagnetic radiation (typically UV)

### photons

light energy is not emitted as a continuous wave but comes in small "packets" of energy called _____; it's energy depends on the frequency of light being considered

### photovoltaic cell

converts a portion of the radiated energy that falls on its surface directly into a potential difference using a piece of semiconducting material

### pixel

the surface of a charge-coupled devide is divided into a large number of small areas called _____ that represents one section of the final image

### polarized light

Electromagnetic radiation consists of oscillating electric and magnetic fields that are always perpendicular to one another. the plane of vibration is the plane that contains the electric field and the direction of propagation. _____ has a fixed plane of polarization; When EM waves reflect from a surface, the reflected reay will tned to be polarized parallel to the surface

### potential divider

uses two resistors to 'divide up' the potential difference supplied by the battery. Each resistro will take a given share which depends on the value of its resistance and the total resistance of the dircuit. For the potential difference supplied to a _____ circuit to be unaffected by the connection of additional components, the extra components added must have a large resistance when compared to the total resistance of _____; also called a potentiometer.

### power fore a wind generator

the power available to a wind turbine as a result of the kinetic energy of wind; all power cannot be harnessed; equal to one half the area "swept out" by the blades of the turbine x density of air x velocity cubed

### power per unit length

calculates the total power per unit length available as a result of the kinetic energy of waves; assumes a rectangular profile for the waves and in practice all this power cannot be harnessed; equal to one half x amplitude of waves squared x density of water x gravitational field strength x velocity of wave

### energy transfer by progressive (traveling waves)

achieved by oscillations of the medium through which the wave travels but there is no net motion of the medium. In many examples the oscillations of the particles are simple harmonic

### projectile motion

the vertical and hte horizontal components of a projectile's velocity in a uniform field are independant of one another

### quantum efficiency

the ratio of the number of photoelectrons emitted to the number of phoons incident on the pixel; improving the _____ of a CCD would allow images of dimmer sources of light to be recorded, but the quality will not be affected

### radioactive decay

the spontanewous emission of ionizing radiations (alpha, beta, or gamma) from an unstable nucleus; random and spontaneous process; rate of decay decreases exponentially with time

### radioactive half-life

the time taken for the number of nuclei that are available to decay to halve to its origninal value is known as the ____; the number of nuclei available to decay reduce to haplf their value in a fixed constant time

### random error

errors in experimental readings resulting from the readablitlity of the instrument, observer geing less than perfecct, or effects of a cahnge in the surroundings; they can be reduced by repeated readings

### range of magnitude of distances

rame from 10 to the negative 15th (sub-nuclear particles) to 10 to the twenty-fifth (extent of the visible universe)

### range of magnitude of masses

range in magnitude from 10 to the negative 15th (an electron) to 10 to the 50th (mass of the visible universe)

### range of magitude of times

range in magnitude from 10 to the negative 23rd (time it takes to cross a nucleus) to 10 to the 18th (age of the universe)

### rarefraction

the points on a longitudinal wave where all the particles are "far apart" (low pressure)

### Rayleigh criterion

two sources will be just resolvable if the first minimum of the difference patteren from one source is located on top of teh central maximum of the diffraction pattern from the other source

### reflection at a boundry

stays in original medium; tis direction of travel is such that the incident angle (the angle between the incident and the normal) and the reflected angle (the angle between the reflected ray and the normal) are equal

### refractive index

the ratio between the speed of the wave in a vacuum and the speed of the wave in the medium

### resolution

two points on an object may just be resolved on a CCD if the images of the points are at least two pixels apart

### resolution of vectors

Any vector can be split into two or more different vectors that would add together to five the same effect. This process is called ____, and the vector is said to have been resolved in different directions. It is often useful to resolve vectors in two mutually perpendicular (and thus independent) directions

### resonance

occurs when a system is subject to an oscillating force at exactly the same frequency as the natural frequency of oscillation of the system; the amplitude of teh oscillations at _____ will be large

### resultant force

the single force that would have the same affect on an object as a combination of forces

### root mean squared (rms) value

value of the direct current (or voltage) that dissipates power in a resistor at the same rate; also known as rating

### rotating coil

the emf incuded in a coil rotating within a uniform magnetic field is sinusoidal if the rotaino is a t constant speed; changing speed of rotation will change maxiumum value of emf induced and the frequency of the alternating emf

### Sankey diagrams

picrotrial representations of energy conversions; an arrow (left to right) repersents the energy changes taking place; the width of the arrow represents the power or energy involved at a given stage; degraded energy is shown with an arrow up or down

### Schrodinger model of hydrogen atom

assumes that electrons in the atom may be described by wave functions; the electron has an undefined position, but the wuqre of the amplitude of the wave function gives the probability of finding the electron at a particular point

### second law of thermodynamics

implies that thermal energy cannot spontaneously transfer from a region of low temperature to a region of high temperature; total entropy of the universe must always stay the same or increase

### sensors

electrical circuit can be designed to respond to external physical inputs if they include devices whose resistance varies as a result of external factors, called _____

### simple harmonic motion

motion where the acceleration of an object is always directed towards a fixed point and is proportional to its displacement from that fixed point

### Snell's law

when a wave is refracted between two media, the ratio of the angle of incidence to the angle of refraction is a fixed constant that depends on the speeds of wave in each media

### solar heating panel

designed to capture as much thermal energy as possible; typically, this directly heats water that is flowing through the panels which can then be used domestically

### specific latent heat

the amount of energy per unit mass absorbed or released during a change of phase; the change of phase from solid to liquid is called fusion; the change of phase from liquid to gas is called vaporization

### speed

the rate of change of an object; equal to the gradient of a distance-time graph and the area under an acceleration-time graph

### standing (stationary) waves

formed when two waves of identical amplitude and frequency which are travelling in opposite direcitons meet; the result is a wave pattern whose shape does not travel through space; in one half of the wave, all the points along the wave are moving in phase to one another; the other half they are also iin phase with one another but in anti-phase to those in the first half; the amplitude of the wave varies along the length of the wave; no energy being permitted

### Stefan-Boltzmann law

the equation for the total power radiated in black-body radiation is the S.B. contant x surface area x the absolute temperature of the black body to the fourth

### strain gauges

devices whose output voltage depends on any small extension or compression that occurs which results in a small change of length

### principle of superpostion

when two waves of the same type meet, the resulting disturbance at any point and at any time where the waves meet is just the vector sum of the disturbances that would have been produced by each of the induvidual waves

### surface heat capacity

the energy required to raise the temperature of unit area of a planet's surgace by one degree

### systematic error

errors in experimental readings resulting from an instrument with zero error, an incorrect calibration of the instrument, or the observer making the same mistake every measurement; not affected by repeated readings

### temperature

determines the direction of thermal energy transfer between the two objects; thermal energy naturally flows from the hotter object to the cooler object; when two objects have reached a constant temperature, they are said to be in thermal equilibrium; its the measure of the average kinetic energy of the molecules in a substance

### thermal energy conversion

thermal energy may be completely converted to work in a single process but that continous conversions of this energy into work requires a cyclical process and the transfer of some energy from the system

### thermistor

a device whose resistance depends on its temperature; mose common devices have a negative temperature coefficient (NTC), which means increase in temperature causes a decrease in resistance

### condition for translational equilibrium

an object will be in _____ if the resultant force on the object is zero; an object in _____ is either at rest or moving with constant (uniform) velocity in a straight line

### transmission at a boundry

a wave transmitted _____ between two media moves from one medium into the other; its direction of travel changes as a result of refraction as calculated by Snell's law

### transverse waves

involve oscillations that aare perpendicular to the direction of energy transfer; examples are light waves (all EM waves); involve oscillations of particles cannot be propagated in fluids (liquids or gases)

### uncontrolled nuclear fission

takes place in nuclear weapons were chain reactions result in a large amount of energy all being released at once

### unified atomic mass unit

a unit apporpraite for nuclear mass calculations; approximatedly the mass of one proton or one neutron but is defined to be exactly one twelfth the mass of a carbon-12 atom

### uses of polarization

Polarized light can be used in the determination of the concentration of certain solutions that are optically active; can be used in stress analysis where bright colored lines are observed in regions of stressed plastic which have been illuminated by polarized white light

### wave speed

the speed at which the wave pattern passes a stationary observer (the speed of energy transfer by the wave)