G482 Electrons, Waves & Photons definitions

All of the definitions you are expected to know for the G482 paper according to OCR specification.

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  • Created by: Becky0295
  • Created on: 21-03-13 21:05
Electric current
A flow of charge (A)
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Conventional current
A model used to describe the movement of charge in a circuit. - travels from + to -.
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Electron flow
The movement of electrons (usually around a circuit) from - to +.
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Coulomb
The total charge supplied by a current of one ampere in a time of one second.
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Kirchoff's first law
The sum of the currents entering any junction is always equal to the sum of the currents leaving the junction (a form of conservation of charge).
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Potential difference
The electrical energy transferred per unit charge when electrical energy is converted into some other form of energy.
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Volt
Unit of potential difference (1 volt = 1JC-1)
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Electromotive force (emf)
The electrical energy transferre per unit charge when one form of energy is converted into electrical energy (V)
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Resistance
A property of a component that regulates the electric current through it (Ohms)
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The Ohm
Unit of resistance. 1 Ohm = 1VA-1
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Ohm's Law
The electric current through a conductor is proportional to the potential difference across it, provided physical conditions, such as temperature remain constant.
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Resistivity
The ratio of the product of resistance and cross-sectional area of a component and its length.
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Kilowatt-hour
1Kwh = 1000w for 3600s = 3.6 MJ
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Kirchoff's second law
The sum of the e.m.f's is equal to the sum of the p.d's in a closed loop (a form of conservation of energy).
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Progressive wave
A wave that travels from one place to another.
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Longitudinal wave
A wave where the oscillations are parallel to the direction of wave propagation eg. sound
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Transverse wave
A wave where the oscillations are perpendicular to the direction of wave propagation e.g em waves
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Displacement
The distance traveled in a particular direction.
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Amplitude
The maximum displacement of a wave from its mean (or rest) position.
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Wavelength
The smallest distance between one point on a wave and the identical point on the next wave.
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Period
The time taken for one complete pattern of oscillation.
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Phase difference
The difference by which one wave leads or lags behind another.
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Frequency
The number of oscillations per unit time.
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Reflection
When waves rebound from a barrier, changing direction but remaining in the same medium.
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Refraction
When waves change direction when they travel from one medium to another due to a difference in the wave speed in each medium.
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Diffraction
When a wave spreads out after passing around an obstacle or through a gap.
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Plane polarised waves
A transverse wave oscillating only in one plane.
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Interference
The addition of two or more waves (superposition) that results in a new wave pattern.
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Coherence
Two waves with a constant phase relationship.
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Nodes
A point that always has zero amplitude along a stationary wave caused by destructive interference.
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Antinodes
A point of maximum amplitude along a stationary wave caused by constructive interference.
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Harmonics
Whole number multiples of the fundamental frequency of a stationary wave.
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Photon
A quantum of light.
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Work function
The minimum energy required to release an electron from a material.
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Threshold frequency
The lowest frequency of electromagnetic radiation that will result in the emission of photoelectrons from a specified metal surface.
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Other cards in this set

Card 2

Front

A model used to describe the movement of charge in a circuit. - travels from + to -.

Back

Conventional current

Card 3

Front

The movement of electrons (usually around a circuit) from - to +.

Back

Preview of the back of card 3

Card 4

Front

The total charge supplied by a current of one ampere in a time of one second.

Back

Preview of the back of card 4

Card 5

Front

The sum of the currents entering any junction is always equal to the sum of the currents leaving the junction (a form of conservation of charge).

Back

Preview of the back of card 5
View more cards

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