definitions

• Torque of a Couple

  Turning effect due to a couple (Nm)
• Work Done

  Energy converted from one form to another (J)
• Ultimate Tensile Stress (Breaking Stress)

  Max tensile (stretching) force applied before it breaks
• N 1st Law
• N 2nd Law
• N 3rd Law
• Impulse


  FxΔt equals to change in momentum (area under a force-time graph)
• Electric current

  Net flow of charged particles per unit time through a point, amperes (Vector)
• Mean drift velocity

  The average speed of charged particles along the length of a conductor
• Conductor

  A material with a high number density of conduction electrons and so a low resistance
• Semiconductor

  A material with low number density of conduction electrons and so a high resistance
• Insulator


  A material with a number density of conduction electrons nearing 0 and so a very high resistance
• Electromotive force (e.m.f.)


  Energy transferred per unit charge when a type of energy is being converted to electrical energy. Work done on every unit of charge. Vector quantity
• Potential difference (p.d.)

  Energy transferred per unit charge when electrical energy is converted into another form of energy. Work done by every unit of charge
• Resistance


  A property of a component that regulates the current flowing through it. Resistance is the potential difference per unit current
• Ohm's law
• Fuse
• Kirchhoff’s Second law
• Terminal p.d.


  Total p.d. across the "load" (external) resistance
• Potential divider circuit

  Contains 2 components designed to divide up the p.d. in proportion to the resistances of the components
• Phase difference


  Proportion of a cycle by which two waves are "out of sync", measured in radians. Phase difference of 2 points on a wave - amount by which one oscillation leads/lags behind another
• Intensity

  Rate of energy transfer per unit area at right angles to wave velocity
• Refraction

  When waves change direction when they travel from one medium to another due to the difference in wave speed in each medium. Frequency is constant
• Diffraction

  A wave spreads out after passing around an obstacle or a gap
• Polarity

  A wave property that allows us to distinguish between transverse and longitudinal waves
• Plane polarised

  A transverse wave that only oscillates in one direction
• Principle of superposition


  Ability of waves to pass through each other and temporarily occupy the same space and combine then carry on unaffected
• Superposition
• Interference


  Superposition of two or more coherent waves, resulting in a new wave
• Coherence

  2 waves with a constant phase difference over a significant period of time
• Path difference

  Proportion of a wavelength by which two waves are "out of sync"
• Stationary waves

  A wave pattern produced when 2 progressive waves of the same frequency travelling in opposite directions superpose, energy is stored
• Fundamental mode of vibration


  Simplest stationary wave that can be set up where the length of the string is half the wavelength
• Fundamental frequency

  Lowest frequency in harmonics series where a stationary wave forms
• Harmonics


  Whole number multiples of the fundamental frequency of a stationary wave
• Photon


  A quantum of energy of electromagnetic radiation
• ElectronVolt

  The energy change of an electron when it moves through a potential difference of 1 volt
• Photocell


  A component that reduces its resistance when light shines on it due to the photoelectric emissions of electrons
• Work function φ

  Minimum energy required by a single electron to escape the metal surface
• Threshold frequency

  The minimum frequency required to release electrons from the surface of a metal