QCEasy Logo

Definitions

Centripetal Acceleration

The acceleration experienced by any object moving in a circular path directed towards the centre of motion.

Centripetal Force

The force acting on an object travelling in a circle that constantly either pulls or pushes the object in towards the centre of motion.

Conservation of Energy

The energy in a system is never lost or destroyed. It is conserved and transformed into other types of energy.

Coulomb's Law

A law stating that like electric charges repel and opposite electric charges attract with a force proportional to the product of the electric charges and inversely proportional to the square of the distance between them.

Electric Charge

A physical property of an object that causes it to experience a force when placed in an electromagnetic field.

Electric Current

The rate of movement of electric charge carriers from one part of a conductor to another.

Electric Field Strength

The intensity of an electric field at a particular location.

Electric Fields

Regions around an electrically charged particle or object within which a force would be exerted on other electrically charged particles or objects.

Electric Potential Energy (PE)

The capacity of electric charge carriers to do work due to their position in an electric circuit.

Electromagnetic Induction

The production of an electromotive force (EMF) or voltage across an electrical conductor due to its dynamic interaction with a magnetic field.

Electromagnetic Radiation

Radiant energy consisting of synchronized oscillations of electric and magnetic fields or electromagnetic waves propagated at the speed of light in a vacuum.

Electromotive Force

A difference in potential that tends to give rise to an electric current, also written as emf.

Faraday's Law

A law stating that when the magnetic flux linking a circuit changes, an electromotive force (emf) is induced in the circuit, proportional to the rate of change of the flux linkage.

Force

A push or pull between objects that may cause one or both objects to change speed and/or the direction of their motion (i.e., accelerate) or change their shape; scientists identify four fundamental forces: gravitational, electromagnetic, the weak nuclear force, and the strong nuclear force.

Gravitational Field Strength

The net force per unit mass at a particular point in the gravitational fields.

Gravitational Fields

The region of space surrounding a body in which another body experiences a force of gravitational attraction.

Kepler's Laws of Planetary Motion

The first law states that all planets move about the Sun in elliptical orbits having the Sun as one of the foci; the second law states that a radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time; the third law states that the squares of the sidereal periods of the planets are directly proportional to the cubes of their mean distance from the Sun.

Lenz's Law

States that the direction of an induced electric current always opposes the change in the circuit or the magnetic field that produces it.

Magnetic Field

A region of space near a magnet, electric current, or moving electrically charged particle in which a magnetic force acts on any other magnet, electric current, or moving electrically charged particle.

Magnetic Flux

A measurement of the total magnetic field that passes through a given area; a measure of the number of magnetic field lines passing through the given area.

Magnetic Flux Density

The strength of a magnetic field or the number of magnetic field lines per unit area.

Newton's Law of Gravitation

The force of attraction between each pair of point particles that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Normal Force

The force acting along an imaginary line drawn perpendicular to the surface.

Period

The amount of time one cycle or one event takes to occur; in circular motion, period refers to the time taken to complete one revolution.

Uniform Circular Motion

The motion of an object traveling at a constant speed in a circle.

Vector

A quantity that has both magnitude and direction; a vector may be represented pictorially by an arrowed line segment.

Velocity

The rate of change of displacement of an object.

Antiparticle

A particle with the same mass and opposite charge and/or spin to a corresponding particle, for example, a positron and an electron.

Baryon

Composite subatomic particles made up of three quarks.

Baryon Number

A strictly conserved additive quantum number of a system defined by B=1/3(n_q - n_q̅) where n_q is the number of quarks and n_q̅ is the number of antiquarks.

Black-body Radiation

The radiation emitted by a black body from the conversion of thermal energy; a black body is a perfect absorber or emitter of radiation.

Electric Fields

Regions around an electrically charged particle or object within which a force would be exerted on other electrically charged particles or objects.

Electromagnetic Force

One of the four fundamental forces; the electromagnetic force is mediated by photons.

Electromagnetic Wave

Produced by an oscillating electric charge resulting in mutually perpendicular electric and magnetic fields.

Elementary Particle

A particle whose substructure is unknown.

Energy

The capacity to do mechanical work; the higher the energy content, the greater the impact when it is transformed or transferred.

Evidence

In science, data that has been selected as it is considered reliable and valid and can be used to support a particular idea, conclusion, or decision; evidence gives weight or value to data by considering its credibility, acceptance, bias, status, appropriateness, and reasonableness.

Feynman Diagram

A graphical representation of particle interactions showing time along the horizontal axis and space along the vertical axis. The axis may be reversed, however not in this syllabus.

Frame of Reference (FoR)

The abstract coordinate system that defines the location of the observer.

Frequency

Equal to the number of waves that move past a given point in one second.

Fundamental Forces

One of four forces that act between bodies of matter and that are mediated by one or more particles.

Gauge Boson

Carrier or exchange particles that govern particle interaction and the mediation of the four fundamental forces; there are four gauge bosons in the Standard Model: the gluon, photon, Z boson, and W boson.

Inertial FoR

Any frame of reference with respect to which the acceleration of the object of observation remains zero.

Length Contraction

An observer at rest relative to a moving object would observe the moving object to be shorter along the dimension of motion.

Lepton

Particles that are governed by the weak nuclear force and, since they have charge, are also influenced by electromagnetism; there are six leptons in the Standard Model: electron, electron neutrino, muon, muon neutrino, tau, and tau neutrino.

Lepton Number

A conserved quantum number defined by L=n_l - n_l̅ where n_l is the number of leptons and n_l̅ is the number of antileptons.

Magnetic Fields

A region of space near a magnet, electric current, or moving electrically charged particle in which a magnetic force acts on any other magnet, electric current, or moving electrically charged particle.

Mass-Energy Equivalence

∆E = ∆mc²

Meson

Subatomic particles composed of one quark and one antiquark.

Phenomena

Events that are not artificial and can be observed through the senses or can be scientifically described or explained.

Photon

A quantum of all forms of electromagnetic radiation; a gauge boson responsible for mediating the electromagnetic force.

Planck's Constant

A fundamental constant used to describe the sizes of quanta in quantum mechanics.

Postulates of Special Relativity

The first postulate states that the laws of physics are the same in all inertial frames of reference; the second postulate states that the speed of light in a vacuum has the same value c in all inertial frames of reference.

Proper Length

The length measured in the frame of reference in which the object is at rest.

Proper Time Interval

The time interval measured in the frame of reference in which the object is at rest.

Quarks

Subatomic particles governed by the strong nuclear force that constitute hadrons; there are six quarks in the Standard Model: the up, down, charm, strange, top, and bottom quark.

Relativistic Length

The length measured in the frame of reference in which the object is in motion.

Relativistic Momentum

The momentum of an object when measured in the frame of reference in which the object is in motion.

Relativistic Time Interval

The time interval measured in the frame of reference in which the object is in motion.

Rest Mass

The mass of an object when measured in the same reference frame as the observer.

Simultaneity

The relation between two events assumed to happen at the same time in a frame of reference.

Strong Nuclear Force

One of the four fundamental forces; the strong nuclear force acts over small distances in the nucleus to hold the nucleons together against the repulsive electrostatic forces exerted between the protons; the strong nuclear force is mediated by gluons.

Threshold Frequency

The minimum frequency of a photon that can eject an electron from a surface.

Time Dilation

The difference of elapsed time between two events as measured by observers moving relative to each other.

Wave Model of Light

Uses the characteristics of waves such as wavelength, frequency, and amplitude to describe the behavior of light.