# G482

OCR Physics A

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• Created by: Jasmine
• Created on: 06-06-14 19:37
electric current
a net flow of charged particles
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conventional current
a model used to describe movement of charge from a + to - terminal
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electron flow
movement of electrons from a - to + terminal
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coulomb
unit of electric charge; 1C = 1A x 1s
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Kirchhoff's First Law
the sum of the currents entering any junction is equal to the sum of currents leaving the junction. (charge is conserved)
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mean drift velocity
average velocity of an electron as it travels through a wire due to a p.d.
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potential difference
electrical energy per unit charge when electrical energy is converted into another form of energy
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volt
unit of potential difference and emf; 1V = 1J per s
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electromotive force
electrical energy transferred per unit charge when one form of energy is converted into electrical energy
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resistance
property of a component that regulates the electric current through it
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ohm
unit of resistance; 1ohm = 1V per A
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Ohm's law
the electric current through a conductor is proportional to the potential difference across it, provided physical conditions remain constant
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resistivity
ratio of the product of resistance and cross sectional area of a component and its length (best defined using equation)
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power
rate of doing work
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kilowatt-hour
unit of energy; 1kWh = 3.6MJ
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Kirchhoff's second law
sum of the emfs is equal to the sum of the pds in a closed circuit (energy is conserved)
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longitudinal
oscillations are parallel to the direction of wave propagation
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transverse
oscillations are perpendicular to the direction of wave propagation
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displacement (of a wave)
distance any part of a wave has moved from its mean/rest position
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amplitude
maximum displacement
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wavelength
smallest distance between a point and the identical point on the next wave
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period
time taken for one complete pattern of oscillation
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phase difference
the difference by which one wave leads/lags behind another wave. Measured in radians.
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reflection
when waves rebound from a barrier
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refraction
when waves change direction when they travel from one medium to another due to a difference in wave speed
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diffraction
when a wave spreads out after passing through a gap/around an obstacle
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polarisation
process of turning an unpolarised wave into a plane polarised wave
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plane polarised wave
a transverse wave oscillating in only one plane
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principle of superposition of waves
when two or more waves of the same type exist at the same place, the resultant wave will be found by adding displacements of each wave
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interference
addition of two of more waves that changes wave pattern
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coherence
two waves with a constant phase relationship
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stationary wave
a wave formed by interference of two waves travelling in opposite directions
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nodes
point of zero amplitude
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antinodes
point of maximum displacement
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photon
quantum of energy of electromagnetic radiation
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electronvolt (eV)
energy change of an electron when it moves through a potential difference of one volt. (1.6x10^19 J)
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work function
minimum energy required to release an electron from a material
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## Other cards in this set

### Card 2

#### Front

a model used to describe movement of charge from a + to - terminal

#### Back

conventional current

### Card 3

#### Front

movement of electrons from a - to + terminal

### Card 4

#### Front

unit of electric charge; 1C = 1A x 1s

### Card 5

#### Front

the sum of the currents entering any junction is equal to the sum of currents leaving the junction. (charge is conserved)