# LP Physics

## Terms

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- intensity (scalar; W/m2)
- the amount of energy carried by a wave across a unit area in a unit time.
- angular momentum (vector; J-s)
- the cross product of the distance an object is from a point and its momentum with respect to this point.
- magnetic flux (scalar; T-m2)
- the total sum of magnetic field vectors passing perpendicularly through a surface. According to Faraday's law, the rate of change of the magnetic flux through a surface is proportional to electromotive force generated on the closed loop containing the surface.
- quanta
- discrete units of energy.
- momentum (vector; kg-m/s)
- see linear momentum or angular momentum.
- half-life
- the time required for half of a radioactive sample to decay.
- amplitude (scalar; m)
- the maximal displacement of an object in simple harmonic motion; the peak-to-peak height of a wave.
- self-inductance
- the generation of an electromotive force in a closed circuit due to a changing current in that circuit.
- elastic modulus (scalar; N/m2)
- the ratio of stress to strain.
- radiation
- the transport of heat in the form of electromagnetic waves.
- kinetic theory of gases
- a model of an ideal gas that treats it as a collection of molecules undergoing motion according to Newton's laws of classical mechanics and predicts macroscopic quantities such as pressure and temperature in terms of molecular properties, such as the velocity of the molecules.
- kinetic energy (scalar; J)
- the energy of an object in motion.
- resonance
- a vibration produced in an object at its natural vibration frequency, or a multiple of it, due to a nearby object vibrating at this frequency.
- rest mass (scalar; kg)
- the mass of an object, measured by an observer at rest with respect to the object.
- isothermal
- at constant temperature.
- longitudinal wave
- a wave in which points on the wave move parallel to the direction of wave propagation.
- resultant
- the sum of two or more vectors.
- dielectric constant (scalar)
- an intrinsic property of a substance that indicates the amount of charge induced in the substance when it is placed in an electric field.
- mole
- the measure of the number of objects or particles. One mole is 6.02×1023 objects (Avogadro's number).
- loudness (scalar; decibels)
- the intensity of a sound wave compared to a set standard, namely, the lowest threshold of human hearing.
- focal point
- the point at which light rays from a mirror or lens intersect.
- nuclear fusion
- the process of two light nuclei coming together to form a heavier nucleus.
- ampere (A)
- the SI unit of measurement of current; equivalent to C/s.
- calorimeter
- a device used to measure the specific heat capacity of a substance.
- convex mirror
- a mirror with an outwardly curved surface, such as the outer surface of a sphere.
- virtual image
- an image produced in an optical device, such as a lens or mirror, that is formed by the extension of diverging rays.
- inertial frame
- a set of coordinates that is not accelerating.
- concave mirror
- a mirror with an inwardly curved surface, such as the inner surface of a sphere.
- ray
- a straight line representation of the path of a light wave.
- angular acceleration (scalar; radians/s2)
- the rate of change of angular velocity in time.
- ray diagram
- a drawing of light rays used to analyze a set of optical devices, such as a lens or mirror.
- volt (V)
- the SI unit of measurement of electrostatic potential; equivalent to J/C.
- superposition principle
- the rule for adding waves at the same point together, which states that the resulting wave is the vector sum of all the independent waves.
- universal gravitational constant (G)
- proportionality constant in Newton's law of universal gravitation, a fundamental constant of the universe, with the value 6.67×10-11 N-m2/kg.
- velocity (vector; m/s2)
- the rate of change of position in time.
- electron
- the negatively charged fundamental particles present in ordinary matter, surrounding the nucleus.
- latent heat (scalar; J/kg)
- the heat required for a phase change of a substance per unit mass.
- standard pressure
- a convenient measure of pressure equivalent to 1 atmosphere or 1.01×105 pascal.
- total internal reflection
- the process in which light traveling from a material with a higher index of refraction to a material with a lower index of refraction is reflected at the boundary and no light actually crosses the boundary.
- kilogram (kg)
- the SI unit of measurement of mass.
- direct current (scalar; A)
- a type of electrical current that flows in only one direction. Direct current flows between the terminals of a simple battery when they are connected to a circuit.
- adiabatic
- without the exchange of heat with the external universe.
- joule (J)
- the SI unit of measurement of energy; equivalent to kg-m2/s2.
- standard temperature
- zero degrees Celsius.
- thermal contact
- contact between objects that allows them to influence each other's temperatures.
- circuit
- a closed loop arrangement of elements such as capacitors, resistors, inductors, and batteries, through which electrical current flows.
- vector
- a quantity with magnitude and direction.
- capacitor
- an electrical device for storing separated charge and therefore storing electrostatic potential energy.
- mass spectrometer
- an instrument that separates ionized atoms or molecules based upon their ratio of charge to mass.
- radioactivity
- the process by which some nuclei spontaneously split and emit particles.
- rigid body
- an object in which the relative distance between internal points does not change.
- transverse wave
- a wave pulse in which points on the wave move perpendicular to the direction of wave propagation.
- law of conservation of momentum
- a fundamental law of physics which states that the linear momentum of a system does not change unless an external force acts upon the system.
- spring constant (scalar; N/m)
- the constant of proportionality between the applied force and the resulting change in length of a given spring.
- watt (W)
- the SI unit of measurement of power; equivalent to J/s.
- atomic number
- the number of protons in a nucleus.
- elasticity
- the property of an object to restore its shape after deformation.
- polarization
- a property of transverse waves, especially light waves, that indicates the orientation of the wave displacement with respect to a coordinate system.
- static equilibrium
- the state of an object when all forces acting on it sum to zero.
- isochoric
- at constant volume.
- conduction
- the transfer of heat through a stationary substance; also the movement of ions or electrons through a material.
- ideal gas
- a collection of identical, infinitesimally small particles that interact only by elastic collisions.
- nucleon
- any particle present in the nucleus of an atom, that is, a proton or neutron.
- conservation of energy
- a fundamental law of physics which states that the energy of a system does not change unless an external force acts upon the system.
- resistivity (scalar; Ω-m)
- a measure of how well current flows through a material, per unit length and cross-sectional area.
- pressure (scalar; Pa)
- the ratio of force to the area to which the force is applied.
- heat of vaporization (scalar; J)
- the heat that must be added per unit mass for a phase change of a substance between liquid and gas states. For a change from liquid to solid, the heat of vaporization is released.
- index of refraction (scalar)
- an intrinsic property of a transparent substance, which measures the speed of light in the material compared to the speed of light in a vacuum.
- Young's modulus (scalar; N/m2)
- the ratio of tensile stress to tensile strain.
- elastic collision
- a collision between two objects in which the kinetic energy of both is conserved.
- simple pendulum
- a mass swinging on the end of a massless string under the influence of gravity.
- centripetal force (vector; N)
- the force that holds an object in circular motion, pointed toward the center of the circle.
- emissivity (scalar)
- an intrinsic property of a material indicating how well it radiates heat.
- alternating current (scalar; A)
- a type of electrical current that changes direction regularly in time.
- RC circuit
- a circuit that contains a resistor and a capacitor in series with one another.
- alternating voltage
- an electrostatic potential that changes regularly in time.
- transparent
- having the property of allowing light to pass through.
- tensile strain (scalar)
- the fractional change in length of an object due to an applied tensile force.
- mass (scalar; kg)
- the intrinsic property of matter that causes it to resist acceleration.
- binding energy
- the energy difference between the mass energy of a nucleus and its separate constituent particles. Binding energy is released when nuclei come together during fusion.
- antinodes
- points on a standing wave that have maximum displacement, due to the constructive interference of the component waves.
- heat of fusion (scalar; J)
- the heat that must be added per unit mass for a phase change of a substance between solid and liquid states. For a change from liquid to solid, the heat of fusion is released.
- sympathetic vibration
- a vibration produced in an object at its natural vibration frequency, or a multiple of it, due to a nearby object vibrating at this frequency. Also called resonance.
- range
- the horizontal distance a projectile travels.
- shear strain (scalar)
- the ratio of the horizontal distance a sheared face moves to the height of the object.
- photoelectrons
- the electrons emitted in the photoelectric effect.
- south pole
- one end of a magnet; the end that attracts the north pole.
- restoring force
- the force exerted by a spring when it is stretched or compressed, which tends to restore the spring to its resting length.
- series
- for circuit elements, elements that are connected so that they have the same electrical current conducted through them.
- threshold frequency
- the minimum frequency that light must have in order to cause photoelectrons to be emitted by a given metal.
- thermodynamics
- the branch of physics concerned with very general properties of matter and energy. It also describes the macroscopic properties of matter in terms of the microscopic properties of its components.
- shear stress (scalar; N/m2)
- the ratio of the tangential force to the area of the face being stressed.
- specific heat capacity (scalar; J/kg-K)
- the heat capacity of a substance per unit mass.
- Carnot cycle
- an ideal series of states through which a heat engine may move, which maximizes the amount of heat converted into work. The Carnot cycle consists of two isothermal processes and two adiabatic processes.
- electromotive force (emf; scalar; V)
- the electrostatic potential difference between the terminals of a circuit or battery when no current is flowing.
- triple point of water
- the temperature of water at which ice, liquid water, and water vapor coexist at thermal equilibrium, defined as 0.01°C or 273.15 K.
- luminous ether
- Ether is the medium on which light waves were once presumed to propagate. The luminous ether does not exist.
- Boltzmann's constant
- a fundamental constant, usually encountered in thermodynamics, with a value of 1.38×10-23 J/K.
- vector component
- the projection of a vector upon a given coordinate axis.
- blackbody
- an object that absorbs all radiation falling on it and radiates it perfectly.
- destructive interference
- the phenomenon in which waves present simultaneously at the same position add together to form a smaller wave, or momentarily cancel entirely.
- transmutation
- the process of one nucleus turning into another through radioactivity.
- uncertainty principle
- the statement that, due to the laws of quantum mechanics, it is impossible to simultaneously exactly measure a particle's position and momentum or to exactly measure a particle's energy for a finite amount of time.
- shear modulus (scalar; N/m2)
- the ratio of shear stress to shear strain.
- standard volume
- the volume of an ideal gas at standard temperature and standard pressure, namely, 22.4 liters.
- constructive interference
- the phenomenon in which waves present simultaneously at the same position add together to form a bigger wave.
- photons
- discrete units of energy; the particles associated with electromagnetic radiation (light).
- electroscope
- a simple device for indicating the presence of net electrical charge.
- nodal points
- points on a standing wave that do not move at all due to the destructive interference of the component waves.
- standing wave
- a wave produced by the superposition of waves traveling in opposite directions, such that the sum is a wave pulse that does not move along the medium (see nodal points, antinodes).
- parallel
- two lines or surfaces that never intersect. Also, for circuit elements, elements that are connected so that they have the same electrostatic potential difference across them.
- normal
- perpendicular.
- real image
- an image produced in an optical device, such as a lens or mirror, that is formed by converging rays.
- normal force (vector; N)
- the force exerted by a surface on an object sitting upon it pointing perpendicular to the surface.
- photoelectric effect
- the emission of electrons by certain metals when the appropriate wavelength of light is shined on them.
- force (vector; N)
- a push or pull that causes an object to accelerate.
- angular displacement (scalar; radians)
- the angle between the initial and final radii after a given time of an object moving in a circle.
- quantum number
- a number describing the quantum state of an object, such as the state of an electron orbiting a nucleus.
- transformer
- a device that is used to pass an alternating voltage from one circuit to another. In the process, the voltage may be increased or decreased.
- radians
- the SI unit of measurement of the size of an angle. A complete circle is 2π radians.
- stationary state
- a quantum state of an electron in which it does not emit radiation.
- general relativity
- the theory of mechanics that treats gravitational fields as equivalent to relative acceleration and introduces the notion that mass curves space and time.
- phase
- the physical state of an object, for example, solid, liquid, or gas. Also, a property of waves indicating the displacement at the initial time.
- opaque
- having the property of not allowing light to pass through.
- thermal expansion
- the phenomenon that most substances increase in volume as their temperature increases.
- permittivity of free space (εo)
- a fundamental constant of the universe that is the proportionality constant in Coulomb's law.
- thermal conductivity (scalar; J/m-K)
- an intrinsic property of a material indicating how well heat transfers through the material.
- refraction
- the bending of light when it passes across the boundary between two media with different indices of refraction.
- inductance (scalar; H)
- a property of a circuit that is the proportionality constant between the rate of change of the current in that circuit and the emf that this changing current produces.
- diverging lens
- a lens that causes parallel light rays to diverge.
- parent nucleus
- the original nucleus during a radioactive decay.
- wavelength
- the distance between identical points in a wave cycle.
- RLC circuit
- a circuit that contains a resistor, a capacitor, and an inductor in series with one another.
- power (scalar; W)
- the rate of change in energy, or the rate of doing work.
- displacement (vector; m)
- change in position of an object.
- RL circuit
- a circuit that contains a resistor and an inductor in series with one another.
- degrees (°)
- the gradations of a temperature scale; also a unit of measurement of an angle.
- atomic mass
- the total number of nucleons in a nucleus.
- tensile stress (scalar; N/m2)
- the ratio of tensile force to the cross-sectional area perpendicular to the force.
- diffraction
- the process of a wave spreading as it passes around an object or passes through a narrow opening.
- tesla (T)
- the SI unit of measurement of the magnitude of a magnetic field; equivalent to N/A-m.
- emf (scalar; V)
- the electrostatic potential difference between the terminals of a circuit or battery when no current is flowing. Also called electromotive force.
- free-body diagram
- another name for force diagram.
- proton
- the fundamental particle, possessing positive charge, that is present in the nuclei of ordinary matter.
- moment of inertia (scalar; kg-m2)
- the intrinsic property of an object that causes it to resist changes in rotational motion.
- temperature (scalar; K, °C)
- a measure of how hot or cold an object is with respect to a reference object.
- mutual inductance
- when a change in one circuit causes a change in a different circuit.
- buoyant force
- the upward force on an object placed in fluid.
- scalar
- a quantity with magnitude but without direction; expressed as a simple number.
- bulk modulus (scalar; N/m2)
- the ratio of pressure to the resulting compressional strain.
- period (scalar; s)
- the time of one complete cycle of simple harmonic motion; the time for one wave cycle to pass a fixed point.
- electric field (vector; V/m)
- the force felt by a positive unit test charge in a region of space, due to the influence of other charges. Electric fields are produced by stationary and moving charges.
- ammeter
- a device used to measure electrical current.
- current (scalar; A)
- the amount of electric charge passing a point per unit time.
- impulse (vector; N-s)
- the product of the average force acting on an object and the time over which it acts.
- potential energy (scalar; J)
- the energy of an object due to its position or internal structure.
- inelastic collision
- a collision between objects in which the kinetic energy changes, for example, due to deformation or frictional loss.
- henry (H)
- the SI unit of measurement of inductance, equivalent to V-s/A.
- electric flux (scalar; V-m)
- the total sum of electric field vectors passing perpendicularly through a surface. According to Gauss's law, the electric flux through a closed gaussian surface is proportional to the total net charge contained within the surface.
- Newton
- the unit of measurement for force; equivalent to kg-m/s2.
- compressional strain (scalar)
- the fractional volume change of an object due to uniform pressure.
- static friction
- friction that resists an object's beginning motion.
- converging lens
- a lens that causes parallel light rays to converge.
- density (scalar; kg/m3)
- mass per unit volume.
- dispersion
- the effect of separating waves, especially light, into constituent wavelengths by passing through a medium with an index of refraction that varies with wavelengths.
- calorie (cal)
- a unit of energy, defined as the energy required to raise one gram of water one degree Celsius, and equivalent to 4.184 J.
- convection
- the transport of heat due to the motion of heated substance, such as a gas.
- Rydberg constant (R)
- a constant found in the description of the line spectra of gases.
- galvanometer
- a device used to measure electrical current.
- entropy (scalar; J/K)
- a fundamental thermodynamic quantity which measures how much heat energy is unavailable for conversion to work.
- field lines
- a pictorial representation of an electric field or magnetic field or any other vector field.
- critical angle
- the angle of incidence for a light ray, below which total internal reflection occurs.
- generator
- a device that converts mechanical energy into electrical energy.
- neutron
- the fundamental particle, possessing no charge, that is present in the nuclei of ordinary matter.
- dichroic
- having the property of naturally emitting light with only a single polarization.
- daughter nucleus
- the nucleus remaining after a radioactive decay.
- coulomb (C)
- the SI unit of measurement of charge.
- rotational inertia (scalar; kg-m2)
- the intrinsic property of an object that causes it to resist changes in rotational motion. Also called moment of inertia.
- thermometer
- a tool for measuring temperature.
- root mean square (rms)
- a way of averaging, equal to the square root of the average of the squares of a quantity.
- forced vibrations
- the vibrations produced in an object connected to another vibrating object, with the effect of amplifying the vibrations of the first object.
- Compton scattering
- the deflection of electrons by photons.
- Bohr radius
- the average radius of an electron orbiting a single proton, equal to 5.29×10-11 m.
- nucleus
- the positively charged central collection of protons and neutrons in an atom.
- permeability constant (μo)
- a fundamental constant of the universe, which is the proportionality constant in Ampere's law and has the value 1.26×10-6 T-m/A.
- friction
- a retarding force between two objects that inhibits motion.
- nuclear fission
- the process of a nucleus splitting into two nearly equal-sized nuclei.
- isotopes
- atoms with nuclei possessing the same number of protons but different numbers of neutrons.
- linear momentum (vector; kg-m/s2)
- the product of mass and velocity.
- centripetal acceleration (vector; m/s2)
- the acceleration of an object in uniform circular motion which is pointed toward the center of the circle.
- conductor
- a material through which electrical charges can easily flow.
- Avogadro's number
- the number of objects or particles in a mole of substance, namely, 6.02×1023.
- Kelvin (K)
- the SI unit of measurement of temperature.
- angular velocity (scalar; radians/s)
- the rate of change of angular displacement in time.
- charge (scalar; C)
- An intrinsic property of matter that causes it to produce an electric field and, when it is moving, a magnetic field, and to feel a force due to these fields as well.
- equivalence principle
- the principle of general relativity which states that experiments conducted in an inertial frame in a gravitational field and experiments conducted in an accelerating reference frame will give the same results.
- simple harmonic motion (SHM)
- the motion of an object with acceleration proportional to the displacement, resulting in repetitive motion.
- energy level diagram
- a diagram illustrating the discrete energies that an electron orbiting a nucleus may possess.
- resistance (scalar; Ω)
- the proportionality constant between the applied electrostatic potential difference and the resulting current in a circuit.
- thermal equilibrium
- the state of objects in thermal contact when they no longer change each other's temperature.
- ohm (Ω)
- the SI unit of measurement of resistance; equivalent to V/A.
- lines of force
- a pictorial representation of an electric field or magnetic field or any other vector field. Also called field lines.
- reactance (scalar; Ω)
- the apparent resistance of capacitors and inductors to alternating current.
- frequency (scalar; Hz)
- the number of complete cycles of simple harmonic motion per unit time; the reciprocal of period; the number of wave cycles passing a fixed point per unit time.
- gaussian surface
- an imaginary surface-enclosing charge used to calculate the electric field at points on the surface using Gauss's law.
- voltmeter
- a device used to measure electrostatic potential differences between two points.
- induction
- the process by which electromotive forces are generated in a circuit due to changes in a magnetic field.
- magnetic field (vector; T)
- the force felt by a unit positive test charge moving through space, due to the influence of magnets or moving charges. Magnetic fields are produced by moving charges.
- line spectrum
- the specific wavelengths of light absorbed and emitted by a gas. The line spectrum is different for each type of gas.
- work (scalar; J)
- the product of the force exerted on an object and the distance through which the object moves as a result. Work results in a change in energy.
- pitch (scalar; Hz)
- the frequency of a sound wave.
- absorption spectrum
- the specific wavelengths of light absorbed by a gas.
- toroid
- a doughnut shaped coil of wire; a solenoid bent into a closed circle.
- equipotential surface
- an array of positions within an electric field that all have the same electrostatic potential value. A charge may move along an equipotential surface without requiring or releasing energy.
- quantum mechanics
- the laws of physics that apply to objects on the atomic scale.
- ether
- The medium on which light waves were once presumed to propagate. The luminous ether does not exist.
- Planck's constant (h)
- a fundamental constant of the universe, appearing in quantum mechanics, with the value 6.626×10-34 J-s.
- spectrum
- the distribution of wavelengths or frequencies of electromagnetic radiation.
- energy (scalar; J)
- the ability to do work.
- special relativity
- the theory of mechanics for objects moving with velocities close to the speed of light.
- farad (F)
- the SI unit of measurement of capacitance; equivalent to A-s/V.
- north pole
- one end of a magnet; the end that attracts the south pole.
- force diagram
- a diagram displaying all of the forces acting on an object.
- capacitance (scalar; F)
- a measure of how much charge a capacitor can store.
- acceleration (vector; m/s2)
- the rate of change of velocity.
- weight (vector; N)
- the product of mass and gravitational force.
- isobaric
- at constant pressure.
- torque (vector; N-m)
- a push or pull that tends to cause an object to rotate about a fixed point; the rotational analog of force.
- hertz (Hz)
- the SI unit of measurement of frequency; equivalent to s-1.
- work function
- the energy required to release an electron from a metal due to the photoelectric effect.
- Doppler effect
- the change in frequency of a wave produced by a moving source. Approaching sources have a higher frequency, and retreating sources have a lower frequency.
- pascal (Pa)
- the SI unit of measurement of pressure; equivalent to N/m2.
- atomic mass unit (amu)
- the unit of mass appropriate to the nucleus of an atom, equivalent to 1/12 of the mass of the carbon nucleus.
- polarizer
- a device that permits light of only one polarization to pass through.
- heat capacity (scalar; J/K)
- the amount of heat energy required to change the temperature of an object by one degree.
- Lorentz contraction
- the effect that an observer moving with respect to a given object will find the object to be shortened compared with the measurement by an observer at rest relative to the object.
- electrostatic potential (scalar; V)
- the amount of energy per unit positive charge required to move a charge between two points within an electric field.
- time dilation
- the effect that time moves more slowly in an inertial frame moving with respect to a stationary one.
- resistor
- a circuit element that impedes the flow of current.
- beats
- the effect produced by interference of waves of slightly different frequency, producing a pattern of alternating intensity.
- solenoid
- a long straight coil of wire.
- kinetic friction
- friction that acts to resist motion of an object that is already moving.
- British thermal unit (BTU)
- a unit of energy frequently used in engineering, equivalent to 252 calories or 1.054 kJ.
- focal length (scalar; m)
- the distance from the focal point of a lens or mirror to the surface of the lens or mirror.
- insulator
- a material through which electrical charges cannot flow.