# Shared Flashcard Set

## Details

OCR Physics A - G482
Definitions required for the Electrons, Waves & Photons paper
48
Physics
10/05/2012

Term
 Electric current
Definition
 Net movement of charge
Term
 Coulomb
Definition
 1 C is the charge transferred in 1 second by a current of 1 amp
Term
 Potential difference (p.d.)
Definition
 The electrical energy transferred per unit charge when electrical energy is converted into another form of energy
Term
 Electromotive force (e.m.f.)
Definition
 The energy transferred per unit charge when another type of energy is converted into electrical energy
Term
 Volt
Definition
 1 V is 1 joule per coulomb
Term
 Resistance
Definition
 Resistance is potential difference per unit current
Term
 Ohm
Definition
 1 ohm is the resistance when 1 volt of potential difference produces 1 ampere of current
Term
 Resistivity
Definition
 resistivity = (resistance * cross-sectional area)/length
Term
 Kilowatt-hour
Definition
 1 kWh is the energy transferred by a 1 kW device in a time of 1 hour
Term
 Terminal p.d.
Definition
 The potential difference across the total external resistance connected to an e.m.f. source
Term
 Progressive wave
Definition
 A wave that carries energy from one place to another
Term
 Transverse wave
Definition
 A wave in which the oscillation is perpendicular to the direction of travel of the wave
Term
 Longitudinal wave
Definition
 A wave in which particles oscillate parallel to the direction of travel of the wave
Term
 Node
Definition
 A point on a stationary wave where the amplitude is zero
Term
 Anti-node
Definition
 A point on a stationary wave where the amplitude is a maximum
Term
 Principle of Superposition
Definition
 When two or more waves of the same type are in the same place at the same time, the resultant displacement is the sum of the displacements of the individual waves
Term
 Amplitude
Definition
 The maximum displacement of any point on a wave from its equilibrium position; it is always positive
Term
 Wavelength
Definition
 The smallest distance from a point on a wave and a similar point on the next wave
Term
 Period of a wave
Definition
 The time taken for one complete oscillation of a point on a wave
Term
 Frequency
Definition
 The number of oscillations per unit time of any point
Term
 Electron-volt
Definition
 1 eV is the energy change of an electron when it moves through a potential difference of one volt
Term
 Work function
Definition
 The minimum energy required to release an electron from the surface of a metal
Term
 Threshold frequency
Definition
 The minimum frequency of electromagnetic radiation required to release an electron from the surface of a metal
Term
 Mean drift velocity
Definition
 The average velocity of a charge carrier as it travels through a medium due to a potential difference.
Term
 Ohm's Law
Definition
 The current through a conductor is proportional to the potential difference across it at a constant temperature
Term
 Displacement
Definition
 The distance any part of the wave has moved from its mean position; it can be positive or negative.
Term
 Phase difference
Definition
 Angular difference by which one wave or particle leads or lags behind another
Term
 Speed of a wave
Definition
 The distance moved by the wave per unit time
Term
 Coherent
Definition
 Waves with a constant phase difference (same frequency)
Term
 Fundamental mode of vibration
Definition
 The lowest frequency stationary wave for a particular system
Term
 Harmonics
Definition
 Stationary waves for a particular system with higher frequencies than the fundamental
Term
 Conventional current
Definition
 Direction is from positive to negative
Term
 Kirchoff's 1st Law
Definition
 The sum of current entering any point in a circuit is equal to the sum of the currents leaving that same point
Term
 Kirchoff's 2nd Law
Definition
 The sum of e.m.f.s round a loop in a circuit is equal to the sum of p.d.s in that same loop
Term
 Power
Definition
 The rate of energy transfer
Term
 Reflection
Definition
 The bouncing back of a wave from a surface
Term
 Refraction
Definition
 The change in direction of a wave as it crosses an interface between two materials where its speed changes
Term
 Diffraction
Definition
 The spreading of a wave when it passes through a gap or past the edge of an object
Term
Definition
 10^1 m
Term
 Typical wavelength of microwaves
Definition
 10^-2 m
Term
Definition
 10^-5 m
Term
 Typical wavelength of visible light
Definition
 4x10^-7 to 7x10^-7 m
Term
Definition
 10^-8 m
Term
 Typical wavelength of X-rays
Definition
 10^-11 m
Term
Definition
 10^-11 m
Term
 Plane polarised wave
Definition
 A transverse wave that oscillates in only one plane
Term
 Constructive interference
Definition
 When two or more waves meet in phase; the amplitudes add
Term
 Destructive interference
Definition
 when two or more waves meet in anti-phase; the amplitudes subtract
Supporting users have an ad free experience!