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GLOSSARY

WAVES

Amplitude - The maximum distance from the crest to the equilibrium FrequencyThe number of oscillations per second PeriodTime taken for one complete oscillation SpeedDistance 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

degrees and radians)

Refractive index- of a material measures how much it slows down light (Snells 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 wavesspread 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

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NATURE OF LIGHT

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 time

MECHANICS

Vector- Size and direction e.g. displacement

Scalar- only has a size or magnitudee.g. distance Acceleration- rate of change of velocity with time Displacement- How far you have travelled and in what direction Newtons 1st law- Every object continues in its state of rest or uniform motion in a straight

line unless made to change by the total force acting on it

Newtons 2nd law- F= ma Newtons 3rd law- If body A exerts a force on Body B then Body B exerts a same force on

Body A but in the opposite direction

Conservation of energy- Total amount of energy in a system remains constantMATERIALS

Laminar flow- Terminal velocity- Friction force equals the driving force Turbulent flow- Hookes Law- Force is proportional to its extension Tensile stress- Tensile force / area of cross section (Nm-2) Tensile Strain- Extension / original length = no units as ratio Young Modulus- Stress / Strain (Nm-2) also Pa = pressure Plastic deformation- materials that no longer obey Hookes Law and may be permanently

deformed if stretched any further

Brittle- Crack or break with little deformation Ductile- Materials show plastic deformation Hard- Materials which resist plastic deformation usually by denting Malleable- Materials which show large plastic deformation Tough- Materials which are able to withstand impact forces without breaking Elastic Strain energy-