AQA A level Physics Paper 1 accurate Answers

Current - ANSWERSRate of flow of charge Coulomb - ANSWERSThe amount of charge passing a point when a current of 1A flows for 1s Potential difference - ANSWERSThe work done per unit charge in moving a small point positive charge between two points Threshold Voltage for a Diode - ANSWERSThe voltage at which a current will begin to flow at, assumed to be +0.6V if not stated Reverse Bias - ANSWERSWhen very little currency can flow in the reverse direction of a diode Variable Resistor - ANSWERSCan be used to change the current through a circuit can also be called a rheostat NTC Thermistor - ANSWERS(A type of semiconductor) that has decreasing resistance when its temperature increases - negative temperature coefficient Transitional Temperature - ANSWERSThe critical temperature at and below which a superconductor has zero resistivity Semiconductor - ANSWERSA group of materials which conduct electricity (not as well as metals), when their temperature rises they can release more charge carriers and their resistance decreases Resistance - ANSWERSThe ratio of a components potential difference to its current Volt - ANSWERSThe potential difference across a component when 1 joule of energy is used to move a coulomb of charge through a component Ohm's Law - ANSWERSProvided that the physical conditions remain the same, the current through an ohmic conductor is directly proportional to the potential difference across it Ohmic conductor - ANSWERSA material that follows Ohm's law when physical components remain the same Diodes - ANSWERSComponents made from semi conductors that only allow current to flow in one direction Resistivity - ANSWERSThe resistance of a 1m length of wire with a 1m^2 cross sectional area Superconductor - ANSWERSA material that has zero resistivity when it is cooled below its critical temperature Critical Temperature - ANSWERSThe temperature below which a material will have zero resistance and will become a superconductor Power - ANSWERSThe rate of transfer of energy EMF - ANSWERSThe work done in moving a unit charge through a battery Lost Volts - ANSWERSWork done per unit charge in overcoming the internal resistance within a battery Terminal PD - ANSWERSThe potential difference between the two terminals of the power supply Potential Divider - ANSWERSA circuit with a constant voltage source and more than one resistor connected in series that can be used to vary the output voltage Threshold Frequency - ANSWERSThe minimum frequency that must be incident on the surface of a metal for the emission of photoelectrons to occur Electromagnetic Force - ANSWERSA fundamental force that causes interactions between charged particules. Virtual photons are the exchange particles Gravitational Force - ANSWERSA fundamental force which causes attraction between objects with a force proportional to their mass Strong Nuclear Force - ANSWERSA fundamental force with a short range which is attractive between 0.5-3 fm and repulsive between 0-0.5fm Alpha Decay - ANSWERSOccurs in nuclei of 82 protons or more that consists of an alpha particle being emitted Photons - ANSWERSVirtual particles that are discrete packets of energy Antiparticle - ANSWERSOpposite in charge to the particle but have the same rest mass and rest energy PET Scan - ANSWERSPositron Emission Tomography Rest Energy - ANSWERSThe amount of energy that would be produced if all of a particle's mass was transformed into energy Fundamental Particle - ANSWERSA particle that cannot be split up into smaller particles Stopping Potential - ANSWERSThe work done by the potential difference in stopping the fastest moving electrons Electron Volt - ANSWERSThe kinetic energy that an electron has after being accelerated from rest through a potential difference of 1 volt 1 eV = - ANSWERS1.6x10^-19 Joules Ground State - ANSWERSThe lowest energy level that an electron can occupy in an atom (n=1) Excitation - ANSWERSWhen an electron gains the exact amount of energy needed to move up to a higher energy level in an atom Ionisation - ANSWERSThe process when an electron gains enough energy from a photon to leave the ground state of the atom that it's in Ionisation Energy - ANSWERSThe amount of energy needed to remove an electron from the ground state of an atom Radian - ANSWERSThe angle that is equal to the arc length divided by the radius of the circle 2pi radians = 360 degrees Angular Speed - ANSWERSThe angle an object rotated through per second (omega = 2pi x frequency) Frequency - ANSWERSThe number of complete revolutions per second Light Damping - ANSWERSStops oscillations over many time periods (just air resistance etc) Heavy Damping - ANSWERSStops oscillations in few time periods, amplitude gets much smaller each period (like adding a parachute or something) Over Damping - ANSWERSStops oscillating over 1 time period but takes longer to return to equilibrium (eg toilet seat) Critical Damping - ANSWERSAmplitude of oscillation is reduced to zero in the shortest possible time Density - ANSWERSThe ratio of the mass of a substance to its volume Hooke's Law - ANSWERSExtension is directly proportional to force applied up to the limit of proportionality Tensile Stress - ANSWERSThe ratio of the force applied to an object to its cross sectional area Tensile Strain - ANSWERSThe ratio of an object's extension to the original length of the material Breaking Stress - ANSWERSThe lowest stress that's big enough to break a material Ultimate Tensile Stress - ANSWERSThe maximum stress that a material can withstand Young Modulus - ANSWERSThe ratio of stress to strain for a particular material Limit of Proportionality - ANSWERSThe point beyond which force is no longer proportional to extension Brittle Material - ANSWERSDoesn't deform plastically but snaps when the stress on it reaches a certain point Brittle Fracture - ANSWERSWhen a stress applied to a brittle material caused tiny crack at the material's surface to get bigger until the material breaks completely Yield Point - ANSWERSThe point at which a material will continue to stretch without any extra load being applied Elastic Limit - ANSWERSThe maximum amount that a material can be stretched and still return to its original length when all force is removed Elastic Strain Energy - ANSWERSThe energy stored in a stretched material Elastic Collision - ANSWERSA collision in which the total momentum and the total kinetic energy are conserved Inelastic Collision - ANSWERSA collision where momentum is conserved but kinetic energy is not Principle of Conservation of Energy - ANSWERSEnergy cannot be created or destroyed, it can be changed from one form to another, but the total amount of energy in a closed system will not change Scalar - ANSWERSA quantity that only has magnitude no direction Vector - ANSWERSA quantity that has both magnitude and direction Principle of Moments - ANSWERSFor an object in equilibrium, sum of clockwise moments about a point must equal the sum of the clockwise moments about the same point Couple - ANSWERSA pair of equal and opposite coplanar forces that act parallel to one anotherm Moment of a Couple - ANSWERSThe force multiplied by the perpendicular distance between the lines of action of the forces Centre of Mass - ANSWERSThe point where an object's mass may be thought to be concentrated Displacement - ANSWERSThe distance that an object has travelled from its starting point in a straight line in a given direction Velocity - ANSWERSThe rate of change of displacement Freefall - ANSWERSWhen the only force acting on an object is gravity Friction - ANSWERSA force that opposes motion between two surfaces that are in contact Lift - ANSWERSAn upward force that acts on an object moving through a fluid Terminal Speed - ANSWERSThe speed that an object moves when the driving forces match the frictional forces and so the resultant force acting is zero Momentum - ANSWERSThe product of an object's mass and velocity Moment - ANSWERSThe force multiplied by the perpendicular distance from the point to the line of action of the force Impulse - ANSWERSThe product of force and time (also the change in momentum) Work - ANSWERSThe product of force and distance moved in the direction of the force Power - ANSWERSThe rate of doing work Watt - ANSWERSThe rate of energy transfer equal to one Joule per second Efficiency - ANSWERSThe ratio of useful energy output to the amount of energy that is inputted Atomic Number (Z) - ANSWERSThe number of protons in the nucleus of an atom Mass Number (A) - ANSWERSThe sum of the number of neutrons and protons in an atomic nucleus Isotopes - ANSWERSAtoms of the same element with a different number of neutrons Isotopic Data - ANSWERSThe relative amounts of different isotopes of an element present within a substance Progressive Waves - ANSWERSWaves that transfer energy from one place to another without transferring any material Reflection - ANSWERSWhen a wave bounces back after hitting a boundary Refraction - ANSWERSWhen a wave changes direction after entering a new medium as a result of the wave speeding up or slowing down Diffraction - ANSWERSWhen a wave spreads out as it passes through a gap or round an obstacles Transverse Waves - ANSWERSWaves where the displacement of particles is perpendicular to the direction of energy propagation Longitudinal Waves - ANSWERSWaves where the displacement of particles is parallel to the direction of energy propagation Electromagnetic Waves - ANSWERSTransverse waves that transfer electrical and magnetic energy and travel at the speed of light Displacement (waves) - ANSWERSThe distance that a wave has moved from its undisturbed position Amplitude - ANSWERSThe maximum displacement of a wave from its equilibrium postion Polarised Wave - ANSWERSA wave that oscillates in one plane only Wavelength - ANSWERSThe length of one whole wave cycle Superposition - ANSWERSWhen two or more waves cross and the resultant displacement equals the vector sum of the individual displacements Constructive Interference - ANSWERSWhen waves with displacements that are in the same direction meet and have their displacements reinforce to create a larger displacement Period - ANSWERSThe time that it takes a complete cycle or wave oscillation to occur Frequency - ANSWERSThe total number of wave cycles that pass a given point per second Phase Difference - ANSWERSThe amount by which one wave lags behind the other (measured as an angle or fractions of a cycle) Phase - ANSWERSA measurement of the position of a certain point along the wave cycle Path Difference - ANSWERSThe amount by which the path travelled by one wave is longer than the path travelled by another