# Physics AS - Electrons, Waves and Photons

• Created by: Anna
• Created on: 12-01-13 13:36
a spectrum of dark lines across the pattern of spectral colours produced when light passes through a gas and the gas absorbs certain frequencies depending on the elements in the gas
absorption spectrum
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the number of oscillations per unit time, mesaured in hertz
frequency
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the maximum displacement of a wave from its mean, or rest position in metres
amplitude
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the minimum energy required to release an electron from a material, measured in J
work function
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two waves with a constant phase relationship
coherence
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one of the specific energies an electron can have when in an atom
energy levels
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a material with a high number density of conduction electrons and therefore low resistance
conductor
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physical law stating that charge is conserved in all interactions, it cannot be created or destroyed
conservation of charge
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physical law stating that energy cannot be created or destroyed, just transferred from one form or place to another in any closed system
conservation of energy
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a model used to describe the movement of charge in a circuit, from + to - terminal
conventional current
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the lowest frequency in a harmonic series where a stationary wave forms
fundamental frequency
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an equation expressing the wavelength of a particle as a ratio of planck's constant and the particle's momentum, mv
de broglie
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when a wave spreads out after passing around an obstacle or through a gap
diffraction
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the distance travelled in a particular direction, in metres
displacement
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the average velocity of an electron as it travels through a wire due to a p.d.
drift velocity
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the ratio of useful output energy to total input energy
efficiency
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an electrical component designed to heat up, melt and break the circuit, hence stop the current, when a specified amount of electrical current passes through it
fuse
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a form of electromagnetic wave with wavelengths between 10^-16 and 10 nm. used in cancer treatment
gamma ray
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a self-propagating transverse wave that can travel in a vacuum
electromagnetic
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the electrical energy transferred per unit charge when one form of energy is converted into electrical energy
electromotive force
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the process of diffracting an electron through a gap, usually between atoms in a crystal structure, an example of wave-particle duality
electron diffraction
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whole number multiples of the fundamental frequency of a stationary wave
harmonics
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the energy change of an electron when it moves through a p.d. of one volt.
electronvolt
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a pattern of colours of light, each colour having a specific wavelength
emission spectrum
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a form of electromagnetic wave with wavelengths between 740 nm and 10 mm. used in remote controls
infrared
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the energy incident per square metre of a surface per second, measures in Watts per metre squared
intensity
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the addition of two or more waves (superposition) that results in a new wave pattern
interference
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the resistance of a battery or cell, measured in ohms
internal resistance
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a graph to show how the electric current through a component varies with the potential difference across it
I-V graph
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unit of energy, used by energy companies when charging for electricity
kilowatt-hour
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the sum of the currents entering any junction is always equal to the sum of the currents leaving the junction
Kirchhoff's first law
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the sum of the e.m.f.s is equal to the sum of the p.d.s in a closed loop
Kirchhoff's second law
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a component that changes its resistance with changes in the light intensity. dark = high resistance
light dependent resistor
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a component that only allows electrical current to pass through it in one direction and that emits light when a p.d. is applied across it
light emitting diode
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a spectrum produced by a material that contains only certain frequencies due to electron transitions between energy levels
line spectrum
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a form of electromagnetic wave with wavelengths between 10 nm and 370 nm. causes sun tanning
ultraviolet
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a physical law describing the change in intensity of a transverse wave passing through a Polaroid analyser
malus' law
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a form of electromagnetic wave with wavelengths between 1 mm and 1 m. used in mobile phones
microwaves
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light waves with a single frequency or wavelength
monochromatic
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a form of electromagnetic wave with wavelengths between 10 pm and 0.1 nm
X ray
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the electric current through a conductor is proportional to the potential difference across it, provided the temperature is constant
Ohm's law
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the time taken fro one complete pattern of oscillation, measured in seconds
period
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the difference by which one wave leads or lags behind another. in phase waves are in step with each other and waves that are completely out of phase are half a wavelength apart, measure in radians
phase difference
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a component that reduces its resistance when light shines on it due to photoelectric emission of electrons
photocell
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the emission of electrons from the surface of a material when electromagnetic radiation is incident on the surface
photoelectric effect
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a transverse wave oscillating in only one plane
plane polarised
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the electrical energy transferred per unit charge when electrical energy is converted into other forms
potential difference
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a type of circuit containing two components designed to divide up the p.d. in proportion to the resistances of the components
potential divider
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the rate of doing work, measured in watts
power
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a discrete, indivisible quantity
quantum
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unit of angle or phase difference
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a form of electromagnetic wave with wavelengths 1 m to 100 km. used in telecommunications
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when waves rebound from a barrier, changing direction but remaining in the same medium
reflection
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when waves change direction when they travel from one medium to another due to a difference in the wave speed of each medium
refraction
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the property of a component that regulates the electric current through it
resistance
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the ratio of the product of resistance and cross-sectional area of a component and its length
resistivity
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a line relating to a specific frequency either missing from an absorption spectrum or present in an emission spectrum
spectral line
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a collection of waves with a range of frequencies, e.g. visible and electromagnetic
spectrum
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a wave formed by the interference of two waves travelling in opposite directions
stationary
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the principle that states when two or more waves of the same type exist at the same place the resultant wave will be found by adding the displacements of each individual wave
superposition
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a component that changes its resistance depending on its temperature. in an NTC, the resistance reduces with increased temperature
thermistor
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the lowest frequency of electromagnetic radiation that will result in the emission of photoelectrons from a specified metal surface
threshold
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the smallest distance between one point on a wave and the identical point on the next wave, measured in metres
wavelength
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the theory that states all objects can exhibit both wave and particle properties
wave-particle duality
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an experiment to demonstrate the wave nature of light via superposition and interference
Young's double slit
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## Other cards in this set

### Card 2

#### Front

the number of oscillations per unit time, mesaured in hertz

frequency

### Card 3

#### Front

the maximum displacement of a wave from its mean, or rest position in metres

### Card 4

#### Front

the minimum energy required to release an electron from a material, measured in J

### Card 5

#### Front

two waves with a constant phase relationship