# Physics definitions

Scalar
A quantity with just magnitude
1 of 83
Vector
A quantity with magnitude and direction
2 of 83
Displacement
Distance in a particular direction
3 of 83
Velocity
The rate of change of displacement
4 of 83
Acceleration
The rate of change of velocity
5 of 83
Instantaneous speed
The speed at a given time ( can be seen as the gradient on a distance time graph)
6 of 83
Average speed
Ratio of distance to time
7 of 83
Newton
The force required to give a mass of 1kg the acceleration of 1ms^-2
8 of 83
Terminal velocity
The maximum speed of an object as a result of an equal drag to driving force ( usually the force of gravity)
9 of 83
Center of gravity
The point through which the weight of an object can be considered to act
10 of 83
Couple
a pair of equal, parallel forces that produce a rotation
11 of 83
Torque
One of the forces x the perpendicular distance between the forces
12 of 83
Moment
Force x perpendicular distance between the force and the pivot/given point
13 of 83
Thinking distance
The distance a vehicle travels from the instance the driver sees the need to apply the brakes and the instance that the brakes are applied
14 of 83
Braking DIstance
The distance that the vehicle travels between the instance that the brakes are applied to the instance that the vehicle comes to a complete stop
15 of 83
Stopping Distance
The sum of the thinking distance and the braking distance
16 of 83
work done
Force multiplied by the distance in which the force is acting
17 of 83
Joule
The work done when a force of 1N moves its point of application 1m in the direction of the force
18 of 83
Conservation of Energy
Energy can not be created or destroyed but may be transferred from one form to another
19 of 83
Power
The rate of doing work
20 of 83
Watt
1 joule per second`
21 of 83
Tensile force
Stretching force; two equal and opposite forces are required to put an object under tension
22 of 83
Compressive force
Squeezing/Squashing ; two equal and opposite forces acting towards the object.
23 of 83
Extension
Change in length from the original length
24 of 83
Elastic limit
The point in which an extended or deformed object will no longer return to its original shape
25 of 83
Stress
Force per unit Cross sectional area
26 of 83
Strain
Extension per unit length
27 of 83
Young's modulus
Ratio of stress to strain ( Stress/Strain)
28 of 83
Ultimate Tensile Strength
That maximum stress an object can endure before fracture
29 of 83
Elastic deformation
The deformation of an object which will return to its original shape when the force is removed
30 of 83
Plastic deformation
The deformation of an object that has resulted in the permanent deformation when the force is removed
31 of 83
Weight
W = mass x acceleration due to gravity (g)
32 of 83
Electric current
The net flow of charged particles per unit time through a point
33 of 83
Conventional current
A model used to describe the movement of charged particles in a circuit
34 of 83
Electron flow
The movement of electrons around a circuit. Negative to positive
35 of 83
Electric charge
(C), 1 coulomb being the total charge supplied by a current of 1 ampere in a time of 1 second
36 of 83
elementary charge
The charge on one electron is 1.6x10^-19
37 of 83
Kirchoff's 1st law
The sum of the current flowing into a junction is equal to the sum of the current flowing out of the junction as charge is conserved
38 of 83
Mean drift velocity
The average speed of charged particles along the length of a conductor
39 of 83
Conductor
A material with a high number density of conduction electrons and therefore a low resistance
40 of 83
Semi conductor
a material with a low number density of conduction electrons and therefore a high resistance
41 of 83
Insulator
A material with a number density of conduction electrons nearing 0 and therefore a very high resistance
42 of 83
Electromotive force (emf)
Energy transferred per unit charge when a type of energy is being converted to electrical energy.
43 of 83
Potential difference (pd)
Energy transferred per unit charge when electrical energy is converted into another form of energy
44 of 83
Power
Work done per unit time
45 of 83
Resistance
Potential difference across a component per unit current
46 of 83
Ohm's law
the current that flows through a component is directly proportional to the potential difference across it providing physical properties such as temperature remain constant
47 of 83
Kirchoff's 2nd
The sum of the emfs around a loop is equal to the sum of the pds around the same loop - conservation of charge
48 of 83
Internal resistance
The resistance of an emf source eg; a cell
49 of 83
Potential divider circuit
A type of circuit containing two components designed to divide the pd in proportion to the resistances of the components
50 of 83
Progressive waves
move through a material transferring energy from one position to another
51 of 83
longitudinal waves
motion of the oscillation of particles is parallel to the direction of the propagation
52 of 83
Transverse waves
Motion of the oscillations of particles is perpendicular to the direction of the propagation
53 of 83
Amplitude
Maximum displacement from the point of equilibrium
54 of 83
Wavelength
The smallest distance between waves - peak to peak / trough to trough
55 of 83
Period
The time taken to complete one full oscillation ( peak to peak)
56 of 83
frequency
The number of oscillations passing per second ( f=1/T)
57 of 83
Phase difference
the proportion of a cycle by which the two waves are "out of sync"
58 of 83
Wave speed
Speed with which energy is transmitted by a wave v=fλ
59 of 83
Intensity
Rate of energy transfer per unit area (at right angles to wave velocity)
60 of 83
Reflection
When waves rebound from a barrier resulting in a change of direction
61 of 83
Refraction
When waves change direction when they travel from one medium to another due to difference in wave speed in each medium
62 of 83
Diffraction
When a wave spreads out after passing around and obstacle or through a gap
63 of 83
Electromagnetic waves
A self-propagating transverse wave that doesnt require a medium to travel through
64 of 83
Polarity
A wave property that distinguishes between transverse and longitudinal waves
65 of 83
Plane polarised
A transverse wave that only oscillates in one direction
66 of 83
Principle of Superposition
the ability for a wave to pass through each other and then continue unaffected
67 of 83
Interference
The superposition of 2 or more coherent waves resulting a new wave/
68 of 83
Coherence
two waves with a constant phase relationshop over a significant period of time
69 of 83
Path difference
The proportion of the wavelength that the 2 waves are 'out of sync'
70 of 83
Constructive interference
When two waves superimpose to create an increased amplitude
71 of 83
Destructing interference
When two waves superimpose to create a reduced amplitude
72 of 83
Stationary waves
A wave pattern produced when two progressive waves of the same frequency travelling in opposite directions superimpose, energy is stored rather than transferred from on place to another
73 of 83
Antinode
Point of maximum amplitude along a stationary wave
74 of 83
Node
A point that has 0 amplitude along a stationary wave as a result of destructive interference
75 of 83
Fundamental mode of vibration
The simplest stationary wave that can be set up where the length of the string is have the wavelength
76 of 83
Fundamental frequency
Lowest frequency in harmonics series where a stationary wave forms
77 of 83
harmonics
Whole number multiples of the fundamental frequency of a stationary wave
78 of 83
Photon
A quantum of energy of EM radiation
79 of 83
ElectronVolt
The energy change of an electron when it moves through a potential difference of 1 volt
80 of 83
Work function φ
minimum energy required by a single electron to escape the metal surface
81 of 83
Threshold frequency
The minimum frequency required to release electrons from the surface of a metal
82 of 83
De Broglie equation
λ=h/mv - an equation expressing wavelength as a ratio of planck's constant and the particles momentum
83 of 83

## Other cards in this set

### Card 2

#### Front

A quantity with magnitude and direction

Vector

### Card 3

#### Front

Distance in a particular direction

### Card 4

#### Front

The rate of change of displacement

### Card 5

#### Front

The rate of change of velocity