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247 terms

IB Physics Vocabulary

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absolute uncertainty
a direct statement of the confidence limits of a reading
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 ...
acceleration
the rate of change of velocity in a particular direction; a vector quantity
accuracy
the measured value is close to the true value; small systematic error
activity
the rate of decay of a radioactive source; the number of nuclei tht decay per unit time
adiabatic
A _____ change is one that takes place without any energy transfer to or from the gas.
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.
amplitude
the maximum displacement from the mean (during one oscillation)
analogue
encodes the information using a range of possible values
analyser
a polerizer used to dectect polarized light
angular frequency
used in SHM; 2pi divided by the period
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).
antinodes
a point on a standing wave that has the maximum amplitude
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.
Avogadro constant
the number of atoms in 0.012 kg of carbon-12; one mole
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
binary numbers
numbers to the base of 2; the only possible digits are 1 or 0
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.
bit
a single binary digit, which will be either 1 or 0
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
Brewster's law
At one particular angle of incidence, EM will be completely polarized
Capacitance
the charge divided by the potential difference
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.
types of charge
positive and negative
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)
conductors
a material that allows the flow of charge through it
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
crest
the peak of a transverse wave (the point of maximum positive displacement)
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
decay constant and half-life
ln2/decay constant
decimal numbers
numbers to the base of 10
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 _____.
derived unit
a unit that is defined in terms of fundamental units
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
digital
encodes the information using only two possible values (1 or 0)
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
displacement
the distance from the origin in a particular direction; a vector quantity
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 current
rate of flow of charge
electric potential difference
the energy difference per unit charge
electric power dissipation
a device that is the pboduct of the potential difference across it and the current flowing through it
electromagnetic (EM) waves
travel with the same speed in a vacuum
'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
e.m.f.
total energy dissipated per unit charge around a circuit; electromotive force
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
the work that has been done on a body; scalar quantity
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
energy density
the energy liberated per unit mass of fuel consumed; measured in Joules per kilogram
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)
entropy
a system property that expresses teh degree of disorder in the system
equation of state for ideal gas
PV=nRT
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
fractional uncertainty
the ratio between the absolute unertainty and the recorded value
frequency
the number of completed oscillations in a given period of time; measured in hertz
frequency vs. period
Time period = 1/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
fundamental unit
a unit that is defined from first principles
fundimental units in SI units
kilogram; meter; second; ampere; mole; kelvin
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
graviational field strength at a planet's surface
g=G(M/square of r)
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
hydroelectric schemes
use gravitational potential energy of water to generated electrical energy
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
instantaneous
value at one particular instant of time
insulator
a material tht does not allow the flow of charge through it
intensity
the power per unit area that is received by the observer; related to amplitude of the wave; intensity=power received/area
internal energy
total potential and random kinetic energy of the molecules of the substance
internal resistance of a battery
the effective extar resistance that is added to a circuit by the battery
isobaric
a change that takes place at constant pressure
isochoric (isovolumetric)
change that takes place at a constant volume
isothermal
change that takes place at constant temperature
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
kinetic energy
the energy that a body has as a result of motion; scalar quantity
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
linear momentum
the procuct of an object's mass and its velocity; a vector quantity
longitudinal waves
involve oscillations that are in the same directon as the direction of energy transfer; sound waves are an example
magnetic fields
moving charges give rise to _____
magnetic flux
the magnetic field strength x the area under consideration x the angle between the magnetic field and the normal to the surface
magnification
the ratio of the length of the image on the CCD to the length of the object
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
neutron number, N
the total number of neutrons in a given nucleus
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
node
a point on a standing wave that never moves; it's amplitude is always zero
non-Ohmic conductor
conductors that do not obey Ohm's law; the graph of potential difference vs. current is not a straight line
non-renewable energy sources
energy soruces that can be used up and eventually run out
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
nucleon
the collective name for protons and neutrons; the particles that make up the nucleus
nucleon number, A
the total number of protons and neutrons in a given nuclide
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
photon energy
equal to planck's constant x frequency of EM radiation
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
polarizer
any device that produces plane-polarized light from an unpolarized beam
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
the rate of doing work, which is the same as transferring energy; a scalar quantity
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
precision
A _____ reading is one with a small random error; uncertainty is small
pressure
the force perunit normal area; the area at right angles to the force
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
proton number, Z
the total number of protons in a given nuclide
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 decay law
radioactive decay is exponential
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
renewable energy sources
energy sources that cannot be used up
resistance
the ratio between potential difference and current
resistivity equation
risistivity in (ohms x length) divided by the cross-sectional area
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
scalars
quantities that only have magnitude
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 heat capacity
the energy required to raise a unit mass of a substance by one 1 Kelvin
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
the non-mechanical transfer of energy between a system and its surroundings (heat)
thermal capacity
the energy required to raise its temperature by 1 Kelvin
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)
trough
the lowest point on a transverse wave (the maxiumum negative displacement)
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
vectors
quantites that have magnitude and direction
velocity
the rate of change of displacement in a particular direction; a vector quantity
wave equation
velocity of a wave = frequency x wavelength
wave speed
the speed at which the wave pattern passes a stationary observer (the speed of energy transfer by the wave)
wavelength
the shortest distance between two points that are in phase with one another
weight
the pull of gravity on an object; measured in Newtons
work
the product of the force and the component of the displacement of the point of application of the force on the object that is in the same direction as the force