G482 Electrons Photons and Waves Definitions

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  • Created by: Molly
  • Created on: 30-12-12 11:59
Absorption Line Spectrum
A dark line of a unique wavelength seen in a continuous spectrum.
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Amplitude
The maximum displacement of a particle from it's equilibrium position,
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Antinode
A point on a stationary wave with maximum amplitude.
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Charge Carrier
Any charged particle, such as electrons, responsible for a current.
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Coherent
Two sorces are coherent when they emit waves with a constant phase difference,
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Compression
A region is a sound wave where the air pressure is greater than its mean value.
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Constructive Interference
When two waves reinforce to give increased amplitude.
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Coulomb
The SI unit of electrical charge. A charge of 1C passes a point when a current of 1A flows for 1sec. 1C = 1As
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Destructive Interferance
When two waves cancel to give decreased amplitude.
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Diffraction
The spreading of a wave when is passes through a gap or past the edge of an object.
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Dispersion
The splitting of light into its different wavelengths
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Einstein relation
This refers to the equation for the energy of a photon: E=hf and E=hc/f
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Electrolyte
An electrically conducting solution. The conduction is due to positive and negative ions in the solution.
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Electromagnetic Spectrum
A family of waves that travel through a vacuum at a speed of 3.0x10 8 ms-1
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Electromotive Force (e.m.f)
Th energy gained per unit charge by charges passing through a supply. Unit JC-1 or V
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Electronvolt
The energy gained by an electron travelling through a p.d. of 1 volt. 1 eV = 1.6x10-19 J
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Elementary Charge
The smallest unit of charge that a particle or an object can have. It has a magnitude of 1.6x10 -19 C
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Emission Line Spectrum
A sharp and bright line of a unique wavelength seen in a spectrum.
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Energy Level
The quantised energy states of an electron in an atom.
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Frequency
The number of oscillations of a particle per unit time (Hz)
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Fundamental Frequency
The lowest frequency stationary waves for a particular system.
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Ground State
The lowest energy state that can be occupied by an electron in an atom.
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Intensity
The power transmitted normally through a surface per unit area. Intensity (W m -2) = power / cross-sectional area.
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Interference
The formation of points of cancellation and reinforcement when two coherent waves pass through each other.
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Internal Resistance
The resistance of an e.m.f. source. Th internal resistance of a battery is due to its chemicals.
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I-V characteristics
A graph of current against voltage for a particular component. You can identify a component from its I-V graph.
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Kirchhoff's First Law
The sum of the currents entering any point (or junction) on a circuit is equal to the sum of the currents leaving that same point. The law conveys the conservation of charge.
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Kirchhoff's Second Law
The sum of the e.m.f.s round a loop in a circuit is equal to the sum of p.d.s in that same loop.
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Light-emitting diode
A semiconductor component that emits light when it conducts.
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Longitudinal Wave
A wave in which particles oscillate along the direction in which the wave travels.
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Lost Volts
The difference between the e.m.f. and the terminal p.d. It is also equal to the voltage across the internal resistance.
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Mean drift Velocity
The average speed of charged particles along the length of a conductor.
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Node
A point on a stationary wave with zero amplitude.
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Ohm's Law
The current in a metallic conductor is directly proportional to the potential difference across its ends, provided its temperature remains constant.
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Path Difference
The difference in the distance traveled by two waves from coherent sources at a particular point.
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Phase Difference
The fraction of a cycle between the oscillations of two particles, expressed in degrees.
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Potential Divider
A circuit in which two or more components are connected in series to a supply. The output voltage from the circuit is take across one of the components.
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Power
The rate at which energy is transferred. Or the rate at which work is done.
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Principle of superposition
When two or more waves meet at a point, the resultant displacement is the sum of the displacements of the individual waves.
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Progressive Wave
A wave that carries energy from one place to another.
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Rarefaction
A region in a sound wave where the air pressure is less than its mean value.
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Resistor
An electrical component whose resistance in a circuit remains constant. Its resistance is independent of current or potential differences
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Semiconductor Diode
An electrical component made from a semiconductor material (e.g. silicon) that only conducts in one direction. A diode in "reverse bias" has an infinite resistance.
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Stationary Wave
A wave pattern produced when two progressive waves of the same frequency travelling in opposite directions combine. It is characterised by nodes and antinodes. Also known as a standing wave.
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Terminal p.d.
The potential difference across the external resistor connected to an e.m.f.sourse.
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Threshold Frequency
The minimum frequency of the electromagnetic radiation that will eject electrons from the surface of a metal.
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Threshold Voltage
The minimum forward bias voltage across a light-emitting diode (LED) when it starts to conduct and emit light.
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Transition
When an electron makes a "jump" between two energy levels.
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Transverse Wave
A wave in which the oscillation is at right angles to the direction in which the wave travels.
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Work Function
The minimum energy required by a single electron to escape the metal surface.
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Other cards in this set

Card 2

Front

The maximum displacement of a particle from it's equilibrium position,

Back

Amplitude

Card 3

Front

A point on a stationary wave with maximum amplitude.

Back

Preview of the back of card 3

Card 4

Front

Any charged particle, such as electrons, responsible for a current.

Back

Preview of the back of card 4

Card 5

Front

Two sorces are coherent when they emit waves with a constant phase difference,

Back

Preview of the back of card 5
View more cards

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