IB Physics Terminology

All IB Physics Terminology

(HL) decay constant

probability that an individual nucleus will decay in a given time interval

(HL) evidence of nuclear energy levels

alpha and gamma decay

(HL) evidence of the existence of the neutrino

continuous spectrum of beta decay

(HL) quantised energy and orbits

arise from the quantisation of anguar momentum in the Bohr model

(HL) work function

energy needed to do the work to overcome the attractive forces that act on the electron within the metal

(HL) threshold frequency

the minimum photon frequency below which no electron can be emitted

(HL) evidence of particle nature of light

photoelectric effect

(HL) additional evidence of particle nature of light

Compton scattering

magnetic flux (HL)

product of mag field strength, cross-sectional area and the cosine of theangle between the magnetic field and the normal to the area

magnetic flux linkage (HL)

product of the magnetic flux through a single coil and the total number of coils

magnetic flux density (HL)

numerically equivalent to magnetic field strength

Faraday's Law (HL)

magnitude of the induced emf equals the rate of change of magnetic flux linkage

Lenz's Law (HL)

the direction of induced current is such as to oppose the change that created the currentinduced emf equals the rate of change of magnetic flux

electric potential (HL)

work done per unit charge moving a small positive test charge in from infinity to a point in an electric field

electric potential energy (HL)

"energy that a charge has due to its position in an electric field

potential gradient (HL)

field strength

equipotential lines (HL)

lines which represent surfaces which are at the same potential, they are perpendicular to field lines

gravitational potential (HL)

the work done per unit mass in moving a mass from infinity to a point in space (always negative)

gravitational potential energy (HL)

the work done in moving a mass from infinity to a point in space

escape speed (HL)

the minimum launch speed from the surface of a planet to overcome the gravitational force

(HL) 1st law of thermodynamics

thermal energy=change in internal energy + work done by a system

(HL) entropy

degree of disorder in a system

(HL) 2nd law of thermodynamics (Clausius)

It is impossible for energy to spontaneously transfer from a body at a lower temperature to one at higher temperature without doing work on the system.

(HL) 2nd law of thermodynamics (Kelvin)

It is impossible to extract energy from a hot reservoir and transfer this entirely into work

(HL) 2nd law of thermodynamics

the total entropy of any isolated system, or the Universe, always increases

(HL) isovolumetric

a process at constant volume (W=0)

(HL) isobaric

a process at constant pressure

(HL) isothermal

A process at constant temperature, Δ𝑈=0

(HL) adiabatic

a process where no energy is supplied to the system (Q=0)

(HL) Carnot cycle

maximum limit of efficiency for a heat engine

torque (HL)

"a measure of force which can make an object rotate about a reference point

moment of inertia (HL)

quantitative measuremeent of rotational inertia of a body

angular momentum (HL)

product of moment of inertia and angular velocuty

conservation of angular momentum (HL)

the total angular momentum of a system is conserved provided that there are no external torques are acting on the system

rotational equilibrium (HL)

the state of net torque equal to zero on a system, constant angular velocity

proper length (HL)

the length of an object measured by an observer at rest relative to the object

proper time (HL)

the time interval measured by an inertial observer at the same place where the events occur

inertial frame (HL)

is one which is either at rest or is moving at constant velocity

first postulate of special relativity (HL)

The laws of physics are the same in all inertial reference frames

evidence for time dilation and length contraction (HL)

muon decay experiments

second postulate of special relativity (HL)

The speed of light is the same in all inertial reference frames

displacement

Vector defining position of as object relative to a reference point

velocity

Rate of change of displacement

speed

Distance travelled divided by time taken

acceleration

Rate of change of velocity

translational equilibrium

the state of net force equal to zero on a system, constant velocity

Newton's 1st law

an object in motion tends to stay in motion unless acted on by a nonzero net force. (law of inertia)

Newton's 2nd law

the net force acting on a body is proportional to the acceleration of the body. (F=ma)

Newton's 3rd law

for every action, there is an equal and opposite reaction

impulse

Change in momentum

linear momentum

Product of the mass and velocity of an object

momentum conservation

the total momentum of a system is conserved provided that there are no external forces are acting on the system

elastic collision

a collision where the total kinetic energy of the system is conserved

inelastic collision

a collision where the total kinetic energy of the system is not conserved

frequency

number of oscillations per second

period

duration of one complete oscillation

centripetal force

the force which acts perpendicular to the linear velocity of an object, directed to the same center

angular velocity

the rate of change of angular displacement

angular displacement

the angle in radians that is displaced

energy density

energy that can be released from 1 m3 of a fuel

work

force times the displacement in the direction of force

power

Rate of energy transfer

efficiency

Ratio of useful output to input

kinetic energy

energy of a mass related to its motion

density

mass per unit volume

thermal energy

non-mechanical energy that is transferred between objects

internal energy

the sum of all potential and kinetic energies in matter

temperature

a measure of the average random kinetic energy of particles in an object

specific heat capacity

energy required to change the temperature of a unit mass of a substance by one degree.

specific latent heat

energy required to change the phase of a unit mass of a substance under constant temperature

evaporation vs boiling

"E: only at the surface, B: throughout the liquid

thermal conduction

transfer of thermal energy through atomic vibrations

convection

movement of groups of atoms or molecules in fluids, that arises from change in density

thermal radiation

transfer of thermal energy by electromagnetic radiation

temperature gradient

change in temperature between two points separated by a distance x as a result of heat transfer by thermal conduction

black body

an object which absorbs all wavelengths of electromagnetic radiation

luminosity

the total power emitted (by the star);

apparent brightness

the (incident) power per unit area on/received at the (surface of) Earth;

energy density

energy that can be released from 1 m3 of a fuel

emissivity

the ratio of the power emitted by a surface to the power emitted by a black body of the same dimensions at the same temperature.

solar constant

Solar intensity that arrives at the top of the atmosphere

greenhouse gases

resonate at the same frequency with ultraviolet light, and absorb the energy, re-emit back to earth

enhanced greenhouse effect

augmentation of greenhouse effect due to human activities

albedo

fraction of the total incoming solar radiation received by a planet that is reflected back out into space (OR: ration of total solar radiation power scattered by a planet to total solar radiation received by a planet)

mole

The number of particles in 12g of Carbon-12 isotope

molar mass

The mass of one mole of identical particles

Avagadro constant

The number of particles in a mole (6.02 x 1023 )

pressure

force applied per unit area

electric current

flow rate of charge, measured relative to force per unit length between parallel current-carrying conductors

resistivity

"RA/L

resistance

ratio of potential difference applied to a device to the current through the device

Ohm's Law

the voltage across a conductor is directly proportional to the current at constant temperature (for Ohmic conductors)

electromotive force (emf)

"energy supplied (work done) by source per unit charge when charge is

Internal resistance

the electrical resistance of the materials a cell is made of.

terminal potential difference

the measure potential difference across the terminal of a cell

simple harmonic motion (SHM)

motion that takes place when the acceleration of an object is proportional to its displacement from its equilibrium position and is always directed toward its equilibrium position

amplitude

maximum displacement from equilibrium

frequency

Rate of oscillations

period

duration of one complete oscillation

phase difference

difference in angular position [between two points or two waves or oscillations]