Physics unit 2 Waves and Electricity definitions

Ampere

the unit of measurement of electric current one amphere(1A) is the movement of one coulomb(1C) oc change per seconds(1s)

Amplitude

The magnitude of the maxiumum displacement reached by an oscillation in the wave

Antinodes

Regions on a stationary wave where the amplitude of the oscillation is at its maximum

Charge

A fundmental property of some particles ot is the ccause of the elctromagnetc force and it is a basic aspect of decribing electrical effects

coherence

Waves which must have the same frequency and a constant phase relationship. (Coherent waves are needed to form a sta le standing wave)

Compression

an area in a longitudinal wave in which the particle oscillations put them closer to eachother than their equilibrium state

conduction band

A range of energy amounts that electrons in a solid material can have which delocalses them to move freel through the solid

constructive interference

The superposition effect of two waves that are in phase producing a larger amplitude resultant wave

Coulomb C

The unit of measurement for charge one coulomb is the quantity of charge that passes a point in a conductor per second when one ampere of current is flowing in the conductor

Charge of an electron

-1.6×10^-19C

Critical angle

The larges angle of incidence that a ray in a more optically dense medium can have and still emerge into less dense medium. Beyond this angle the ay will be totally inernally reflected

Current

The rate of flow of charge

Destructie interference

The superposition effect of two waves that are out of phase producing a smaller amplitude

Diffrction

When a wave passes close by an object or through a gap the wave energy spreads out

Displacement

The position of a particular point on a wave at a particular instant in time measure form the mean(equilibrium) position

Drift velocity

the slow overall movement of the charges in a current

Electric current rule

The sum of current entering a junction is wqual to 0

EMF

A voltage wit the energy coming into the circuit

Electronvolt (Ev)

1Ev=1.6×10^-19J

Excitation

An energy stat for a system that is higher energy than the ground state.

Frequency

The number of complete wave cycles per second

Ground state

The lowest energy level for a system

Interference

The superposition outcome of a combination of waves. Interference only occurs when the waves are coherent

Ionisation Energy

The minimum energy required by an electron in an atom’s ground state in order to remove the electron completely from the atom

Line spectrum

A series of individual lines of colour showing the frequency present in a light source

Longitudinal wave

A wave in which the oscillations occur parallel to the direction of movement of the wave energy

Maxiumum

In a diffraction or interference patter: The bright spots

Minimum

In a diffraction or interference patter: The dark spots

Monochromatic

Containing or using one colour/light of a single wavelength/frequency

Nodes

Regions on a staionary wave where the amplitude of oscillation is 0

Ohm’s Law

The current through a component is directly proportional to the voltage across it, providing the temperature and resistance remain the same.

Time Period

The time taken for one complete oscillation at one point on the wave

Phase

The stage a given point on a wave is through a complete cycle, measured in radians

Photoelectrons

Electrons released from a metal surface as a result of its exposure to electromagnetic radiation

Photons

Packets of electromagnetic radiation energy

Photon energy

E=hf

Phlank’s Constant

6.63 × 10^-34

Polarisation

The 0orientation of the plane of oscillation of a transverse wave. If the wave is polarised, all its oscillations occur in one single plane

Potential difference

The voltage of a component that is using electrical energy in a circuit and transfer this energy to other stores

Potential divider

A circuit designed to provide specific voltage value by splitting an emf across two resistor

Potentiometer

A version of the potential divider in which a single resistance wire is used in two parts to form the two resistances. A sliding connection on the wire can be adjusted to alter the comparative resistances and thus alter the output pd from the potentiometer

Progressive wave

A means for transferring energy via oscillation

Rarefaction

an area in a longitudinal wave in which the particle oscillations put them further apart from each other than their equilibrium state

Refraction

A cange in wave speed and direction when the wave moves from one medium to another

Refractive index

n=c/v

Resistanc

The opposition to the flow of electrical current

Resistivity(ρ)

RA/l

Semiconductors

Materials with lover resistivity than insulator but higher than conductors. Thy usually have small number of delocalised electrons that are free to conduct

Snell’s law

n₁sin(θ)₁=n₂sin(θ)₂

Sonometer

An apparatus for experimenting with the frequency relationships of a string under tension usually consisting of a horizontal wooden sounding box and a metal wire stretched along the top of the box

Stationary/Standing wave

A wave which has oscillations in a fixed space with regions of significant oscillation and regions with zero oscillation, which remain in the same location at all times(nodes and anitnodes)

Stopping voltage

The minimum voltage needed to reduce the photoelectric current to 0 when illuminated with a particular frequency of ligh

superconductivity

The electrical property of a material having 0 resistivity

Superposition

when more than one wave is in the same location the overall effect is the vector sum of their individual displacements at each point where they meet

Threshold frenquency

The minimum frequency of electromagnetic radiation that can cause the emission of photoelectron from a metal

TIR

Waves reflect back into the same medium at a boundary between two media. This requires to conditions to be met:

• the rays is attempting o emerge from the more dense medium

• i>c

Transport equation

I=nAvq

• I is current

• n is number density

• A is cross sectional area of the conductor

• v is the drift velocity

• q is the charge of all the carriers combined

Transverse Wave

A wave in which the oscillations occur perpendicular to the direction of movement of tthe wave energy

Twin-beam oscillscope

An oscilloscope with two inputs. It displays each as a li9ne on the screen and both are shown at the same time to compare inputs

Valence Band

A range of energy amounts that electrons in a solid material can have which keeps them close to one particular atom

Voltage

A measure of the amount of energy a component transfers per unit of charge passing though it

Voltage circuit rule

the sum of emfs equals to the sums of pds

Wave

a means for transferring energy via oscillations

Wave equation

v=fλ

Wave speed

The rate of movement of the wave

Wavefronts

Lines connection points on the wave that are at exactly the same phase position

Wavelength

The distance between a point on a wave and the same point on the next cycle of the wave

Wave=particle duality

The principle that the behaviour of electromagnetic radiation can be described in terms of both waves and photons

Work function

The minimum energy need by an election at the surrface of a metal to be emitted from it