Transcript AS Physics
AS Physics – Module 1 Definitions For each term, think of a definition. After 15 seconds, the definition will appear …as if by magic! Then play the ppt again and see how many you can remember Current Electricity Current “The rate of flow of charge” Potential Difference “The energy transferred when unit charge passes between two points” 1 Volt = “1 Volt = 1 Joule/Coulomb” Resistance “R=V/I” Ohm’s Law “Current is proportional to p.d. provided temperature remains constant” Current Electricity Power “Rate of energy transfer” Kirchoff’s First Law “Conservation of charge – at any junction the algebraic sum of the currents is zero” Kirchoff’s Second Law “Conservation of energy – the algebraic sum of potential differences around a closed circuit is zero” EMF “The energy transferred to unit charge as it passes through a cell” Or “The p.d. across the source when no current flows” Internal Resistance “Energy transferred within a cell as charge flows through it” Current Electricity Peak Value “Maximum displacement from the zero line, labelled either I0 or V0” Peak to Peak Value “Maximum displacement across both directions (+ and -) Time Period “Time for one complete cycle, T” Frequency “Number of cycles (waves) per second, measured in Hertz” root mean square value “The effective d.c. value that would produce the same heating effect in a resistor” Particles Proton “Positive constituent of an atom’s nucleus” Neutron “Neutral constituent of an atom’s nucleus” Electron “Negatively charged particle orbiting the nucleus” Atomic number or Proton number “Number of protons in the nucleus (also equal to number of electrons)” Nucleon number or Mass number “Number of protons and neutrons in an atom’s nucleus” Isotope “A form of an element with the same proton number but different neutron number” Particles Antimatter “Mirror image of a particle with identical mass but opposite charge and other quantum properties” Annihilation “Conversion of mass to energy – particle and antiparticle are converted into a pair of photons” Pair Production “A high energy photon is converted into a pair of particles” Particles Strong Force “Force experienced by hadrons (baryons and mesons)” Weak Force “Force experienced by leptons and hadrons, responsible for changes to quark composition” Electromagnetic Force “Force experienced by charged particles” Gravity “Force experienced by all particles with mass” Particles Fundamental Particles “Can’t be broken down into smaller particles: Leptons are fundamental” Leptons “Electron, muon, tau, (Q=-1 for all), electron neutrino, muon neutrino, tau neutrino and their anti-particles) Hadrons “Baryons: 3 quarks, Antibaryons: 3 antiquarks, mesons: quark and an antiquark” Particles Photoelectric Effect Electrons are emitted from the surface of a metal when the frequency of light is above a threshold value Threshold Frequency The minimum frequency of light needed to cause emission of an electron from a metal Work Function The energy needed to remove an electron from the surface of a metal Electronvolt Amount of energy gained by an electron accelerated through a p.d. of 1Volt Excitation Electron moves up an energy level Ionisation Electron becomes free from the atom Particles Wave-Particle Duality The ability for waves to behave like particles and particles to behave like waves Wave nature of particles Electron Diffraction Particle nature of waves Photoelectric effect deBroglie Wavelength A particle of momentum p should have an associated wavelength λ