# OCR Physics B (Advancing Physics) Yr 1 Glossary

Fully inclusive collection of the definitions for the 1st Yr. collected from the textbook, revision guide and checked against past mark schemes.

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- Created on: 28-04-18 18:35

Acceleration, a

The rate of change of velocity (Vector)

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Accuracy

A measure of how close a measurement is to the true value

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Accurate

Close to the true value

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Aliasing

Whenl lower frequency signals are created due to too lower sampling rate. These lower frequencies are not in the origional signal.

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Alloy

A material composed of two or more metals, or a mixture of metals and other materials

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Amorphous

Atoms are arranged with no large range order, they are arranged randomly within the structure

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Amplitude of a wave

The maximum displacement from the equilibrium position

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Analogue Signal

A signal that varies continuously and is not confined to defined levels

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Antinode

A position of maximum amplitude of oscillation on standing wave

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Antiphase

When two oscillations have a phase difference of pi radians or a path difference of half a wavelength

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bit

The smallest unit of digital information

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Brittle

Breaks by shattering on impact, it undergoes no plastic deformation before fracture

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Brittleness

The tendency of a material to break by crack propagation

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byte

A sequence of 8 bits, coded to represent 256 alternatives

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Calibration

Determining the relation between output and true input value

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Ceramics

Materials made up of bonded atoms with directional and local bonds

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Conductance, G

The ratio of I/V for a circuit component (Unit in Siemens, S)

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Coherence

Two sources of waves a coherent if they have a constant phase difference and the same frequency.

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Compression

When two forces act in opposite directions to compress an object along the line of action of the forces

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Conductivity, Ïƒ (Electrical)

A constant for electrical conductors, which refers to the degree to which a specified material conducts electricity (Unit S/m)

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Conductor (Electrical)

A material which conducts electricity well because it has many free charge carriers

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Conservation of Energy

During any interaction, the total energy before the interaction is the same as the total energy after the interaction

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Conservation of Momentum

During any interaction, the total momentum before the interaction is the same as the total momentum after the interaction (N2)

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Crack propagation

When the stress on a material is concentrated at the tip of a crack, often across a single bond, causing the crack to travel through the material from its surface.

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Cross linking of polymers

When links are added across molecular chains within a polymer making the material stiffer by limiting the bond rotation

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Crystalline

Particles in a material are arranged in a regular pattern over a large range

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Current (Electrical)

The rate at which charge flows through a pointing an electrical circuit (Unit in Amperes, A)

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Density, â´

The mass per unit volume

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Diffraction

The spreading of waves after passing through a gap or past the edge of an obstacle. Spread increased for narrower gap or increased wavelength

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Digital Signal

A signal that has defined levels and is represented by binary number

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Dislocation

A defect in the regular structure of a crystal or crystalline region of a material. Mobile within a pure metal making it ductile.

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Displacement, s

The distance travelled in a specified direction (Vector)

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Dissipation

A transfer of thermal energy resulting in an increase in internal energy, often of the surroundings

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Distance

The separation between two points in space, possibly along a curved path, with no reference to direction (Scalar)

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Drift velocity

The mean velocity of charge carriers in a conductor carrying an electrical current

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Ductile

A material that can easily be drawn into a wire without losing its strength

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Edge Detection

Highlighting only the edges in an image / Multiplying pixel value by 4, then subtracting the total of the 4 neighbouring pixel values. If answer is negative the pixel is made 0 (black)

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e.m.f, Îµ

The energy per unit charge given by any source of electrical supply to the charges set in motion.

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Elastic Deformation

When the material will regain its original shape after the deforming stress is removed

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Elastic Limit

The maximum stress at which an object returns to its original shape after the deforming stress is removed

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Elastic strain energy

The energy stored in a material when it is deformed elasticaly / Can be found as area underneath a F-x graph or per unit volume for area underneath a stress-strain graph

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Elasticity

The ability for a material to return to its original shape after the deforming stress has been removed

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Electronvolt, eV

The work done/kinetic energy gained lk when an electron is moved through a potential difference of 1 volt

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False Colours

Assigning different colours for pixel value ranges. Used to highlight different features of an image.

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Focal length, f

The distance from the centre of the lens to the focal point F

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Focal Point (Focus), F

The point where light from a very distant object on the axis of the lens is brought to a focus by the lens

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Force, F

The rate of change of momentum (N2) / the 'push' or 'pull' of an object associated with a change in its momentum (Unit Newtons, N)

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Fracture

When an object is broken into two or more pieces when placed under stress

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Fracture Stress

The stress at which an object fractures (breaks)

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Fundamental frequency

The smallest frequency of a standing wave, found when the node seperation is half a wavelength

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Grain boundary

The line along which grains meet in a crystalline material

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Gravitational Potential Energy, E-grav

The potential energy of a mass due to its position in a gravitational field

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Hard

Difficult to scratch or dent

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Hardness

A measure of how difficult it is to scratch or dent a material

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Hooke's Law

For small extenstions, force is proportional to extension by F=kx

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Hooke's Law region

The region of a stress strain graph where the stress is proportional to strain, material is deforming elastically

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Impulse

The product FÎ”t summed over the whole action of a force on an object resulting in a momentum change, Î”p = Impulse

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Increasing Brightness

Increasing the lightness of all pixels in an image / Adding a fixed value to all of the pixel values

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Increasing Contrast

Increasing the range of pixel values in an image by multiplying all the pixel values by a fixed value greater than one.

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Inertia

The tendency of any stationary object to remain stationary or of any moving object to continue with the same momentum (N1)

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Insulator (Electrical)

A material which conducts electricity poorly because it has very few free charge carries

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Intensity

The energy per unit time carried by a wave / the energy per unit area on a surface

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Internal resistance, r

The resistance within a source of e.m.f that results in a drop of terminal p.d. when current is drawn from the source

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Iterative model

A mathematical treatment where small changes to variables are made at regular time intervals, Î”t

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Kinetic Energy, E-k

The energy possessed by an object by virtue of its motion

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Kirchoff's 1st Law

At any electrical junction, the total current into the the junction = the total current out of a junction / Conservation of current

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Kirchoff's 2nd Law

Around any electrical circuit, the sum of all the e.m.f.s = the sum of all the p.d.s / Conservation of energy

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Limit of Proportionality

The end of the hookes law region on a stress-strain graph, material is still deforming elastically but not at a constant rate

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Longitudanal waves

When the oscillation of a wave is in the same direction as its direction of travel

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Malleable

Easy to hammer or press a material into a required shape

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Malleability

A measure of how easily a material can be hammered of pressed into a required shape

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Mass, m

The amount of matter in an object (Unit kg)

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Metals

Materials made up of metalically bonded atoms with non-directional and delocalized bonds

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Momentum, p

The product of the mass and velocity of an object (Vector)

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Newton's 1st Law

A stationary object will remain stationary, and a moving object with continue moving with the same momentum unless an external force acts upon it

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Newton's 2nd Law

When an external force acts on an object, it produces a change in momentum / Force = the rate of change of of momentum / F=ma for a constant mass

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Newton's 3rd Law

For every action there is an equal and opposite reaction

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Node

A position of minimum amplitude of oscillation on standing wave

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Noise

Variations, which may be random, superimposed on a signal

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Number density of charge carries, n

The number of mobile charge carriers per unit volume of a conductor

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Path difference

The difference in distance travelled by two waves to the same point

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Percentage Uncertanty

The uncertanty given as a percentage of the measurement

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Phase

Describes the stage in a wave cycle

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Phase difference

The difference in phase angle between two waves of the same frequency

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Pixel

A single picture element

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Plane wavefront

A wavefront which contains no curvature

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Plastic Deformation

When a material undergoes permanent deformation and does not return to its original shape when the deforming stress is removed

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Plasticity

Material can deform permanently

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Polarized wave

When a transverse wave oscillates in a single plane only

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Polycrystalline

A material that is composed of many small, differently oriented grains made up of regularly structured atoms within

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Polymers

Materials made from long chains of molecules

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Precise

Repeated measurements are close together

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Precision

A measure of how close repeated measurements are to each other

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Projectile

An object that is thrown or fired who's subsequent motion is affected by a gravitational field

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Random Error

An error in the results of an experiment which varies each time for the same setup

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Reducing Noise

Reducing the amount of random noise in an image / Replacing pixel values with the median of their neighbouring pixel values

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Refraction

The change in direction of a wave passing from one medium to another caused by its change in speed

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Refractive index, n

The ratio of the speed of light in a vacuum to the speed of light in a material

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Resistivity, â´ (Electrical)

A constant for electrical conductors, which refers to the degree to which a specified material resists the flow of an electrical current (Unit Î©m)

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Repeatable

An experiment can be repeated multiple times to achieve the same results

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Reproducible

An experiment can be repeated by someone else using different equipment or results to achieve the same answer

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Resolution

The smallest detectable change in input

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Response time

The time interval between a change in input and the corresponding change in output

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Scalar

A quantity with magnitude but no direction

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Semiconductor

A material with intermediate conductivity between conductors and insulators, due to having a much lower density of free charge carries than conductors

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Sensitivity

The ratio of the output to the input

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Sensor Circuit

A circuit whose electrical properties depend upon environment variables and which can be used to monitor or measure those variables

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Speed

The distance travelled by an object per unit time with no account to direction (Scalar)

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Standing wave

The superposition of two progressive waves with the same wavelength, moving in opposite directions

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Strain, Îµ

The ratio of extension to original length

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Strain Gauge

A small electrical device which contains long lengths of coiled up wire on a foil back allowing it to detect deformation to a surface. Compression if resistance decreases and tension if restance increaseses.

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Strength

A measure of how much a material can resist being deformed by a force without breaking

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Strong

Large breaking stress, can withstand high stresses without deforming or breaking

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Stiff

Difficult to bend or stretch, small extension per unit force

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Stiffness

A measure of a material's resistance to stretching or bending

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Superposition

When two or more waves meet their displacements can superimpose. The resultant displacement is the sum of the displacements at a given instant

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Systamatic Error

An error in the setup of an experiment which is the same for every repetition using the same setup

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Tension

When two forces act in opposite directions to stretch an object along the line of action of the forces

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Transverse waves

When the oscillation of a wave is perpindular to its direction of travel

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Threshold frequency

The minimum frequency of light that will eject photoelectrons from a given surface

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Tough

Large energy required to break or create new surface area

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Toughness

A measure of how much energy a material can absorb before breaking

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Vector

A quantity with both direction and magnitude

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Velocity

The change in displacement of an object per unit time (vector)

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Wavefront

An imaginary line or surface that moves along with a wave. All points on the wavefront have the same phase.

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Work function, É¸

The minimum energy required to eject photoelectrons from a given surface

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Yield Stress

The stress at which a large amount of plastic deformation takes place with a constant or reduced load

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Ultimate Tensile Strength

The maximum stress a material can withstand before breaking

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Un-Polarized wave

When a transverse wave oscillates in a randomly changing plane

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Young's Modulus, E

A measure of the stiffness of a material given by the ratio of stress over strain

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Valid

The results answer the origional question

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Validity

A measure of how well the results answer the origional question

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Zero error

The output for zero input

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## Other cards in this set

### Card 2

#### Front

A measure of how close a measurement is to the true value

#### Back

Accuracy

### Card 3

#### Front

Close to the true value

#### Back

### Card 4

#### Front

Whenl lower frequency signals are created due to too lower sampling rate. These lower frequencies are not in the origional signal.

#### Back

### Card 5

#### Front

A material composed of two or more metals, or a mixture of metals and other materials

#### Back

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