# As Physics Edexcel

Glossary

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• Created by: Mashal
• Created on: 01-05-11 20:45

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GLOSSARY
WAVES
Amplitude - The maximum distance from the crest to the equilibrium
Frequency ­ The number of oscillations per second
Period ­ Time taken for one complete oscillation
Speed ­ Distance travelled per unit time. Speed is the scalar quantity that is the magnitude of
the velocity vector.
Longitudinal waves- Vibrations are along the direction of travel e.g. sound
Transverse waves- Vibrations are at a right angle to the direction of travel
Standing waves- Positions of the peaks and troughs are not moving
Nodes- are where the amplitude of the vibration is zero
Antinodes- are points of maximum amplitude
Phase- Points that are a whole wavelength apart oscillate in phase
Anti phase- Points that are half a wavelength apart oscillate in anti phase
Path difference- the amount in which one wave lags behind another wave (measured in
Refractive index- of a material measures how much it slows down light (Snell's Law)
Refraction- Change of direction of a wave that occurs when its speed changes
Plane polarised - Only transverse waves show ­ a wave in which oscillations occur in one
plane are plane polarised in that direction
Diffraction in waves- Interaction between waves and solid obstacles= the way that waves
spread out as they come though a narrow gap or go round obstacles
Doppler effect- can be used to measure the speed of objects
Principle of superposition- where two or more waves meet the total displacement at any
point is the sum of the displacements that each individual wave would cause at that point
DC ELECTRICITY
Electric current- rate of flow of charged particles I = (change in) Q / (change in) T
Current- Rate of flow of charge
Potential difference- is the energy per unit charge
Emf - Amount of energy supplied to each unit of charge
Resistance- collision of atoms and electrons = how difficult it is to get a current to flow
Resistivity- Resistance of a material
Internal resistance- A source of EMF has some resistance to electric current within it
Drift Velocity- average velocity of the electrons
Ohms Law- Provided that the temperature and other physical factors remain constant the
current through the wire is proportional to the pd
Coulomb- amount of charge that passes in 1 second when current is 1 ampere
NATURE OF LIGHT

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Photons- particle of light
Photoelectrons- Electrons that escape from the surface of a metal under the presence of
UV light that transfers energy to electrons
Work function- energy required to completely remove one electron from the metal
Threshold frequency- minimum frequency of light below which the emission of
photoelectrons cannot happen for a given surface
Electron volt- 1ev is the energy transferred when an electron travels through a pd of 1 volt
Radiation flux- amount of energy landing on a unit area in a unit…read more