Key Terms and Definitions Flashcards
Acceleration
The rate of change of an object’s velocity. Unit: ms-1
Absorption Line Spectrum
A dark line of a unique wavelength seen in a continuous spectrum.
Ampere
SI unit of electric current.
Amplitude.
The maximum displacement of a particle from its equilibrium position.
Antinode
A point on a stationary wave with maximum amplitude.
Braking Distance
The distance travelled by a vehicle from the moment when the brakes are applied until the vehicle comes to a stop.
Brittle
Describes an object that shows no plastic deformation and breaks just beyond its elastic limit.
Centre of Gravity
The point where the entire weight of an object appears to act.
Charge Carrier
Any charged particles responsible for an electric current. These are electrons in a metal and ions in an electrolyte.
Coherent
Two wave sources are coherent when they emit waves with a constant phase difference.
Components (of a vector)
The magnitudes of a vector quantity in two perpendicular directions.
Compression
A region in a longitudinal wave where air pressure is greater than its mean value.
Compressive
A force that squeezes an object.
Constructive Interference
When two waves reinforce to give increased amplitude.
Coulomb
The amount of charge that passes a point when a current of one amp flows for one second.
Density
The mass per unit volume of a material.
Destructive Interference
When two waves cancel to give reduced amplitude.
Diffraction
The spreading of a wave as it passes through a gap or past the edge of an object.
Displacement
The distance moved by an object in a particular direction.
Ductile
Describes a material that can easily be drawn into wires.
Efficiency
The ratio of useful energy to total input energy for a device, expressed as a ratio.
Elastic
Describes a material which will return to its original shape when the forces acting upon it are removed.
Elastic Limit
The value of stress beyond which an object will not return to its original dimensions.
Elastic Potential Energy
Energy stored in an extended or compressed material.
Electrical Resistance
The ratio of potential difference to current.
Electrolyte
An electrically conducting solution.
Electromagnetic Spectrum
A family of waves that travel through a vacuum at a speed of 3.0 x 10^8 ms-1
Electromotive Force
The energy gained per unit charge by charges passing through a supply.
Electronvolt
The energy gained by an electron travelling through a p.d of 1 volt.
Elementary Charge
The smallest unit of charge that a particle of object can have. It has a magnitude of 1.6 x 10^-19 C.
Emission Line Spectrum
A sharp and bright line of a unique wavelength seen in a spectrum.
Energy Level
The quantised energy states of an electron in an atom.
Force Constant
The ratio of force to extension for a spring or a wire.
Frequency
The number of oscillations of a particle per unit time.
Fundamental Frequency
The lowest frequency stationary wave for a particular system.
Gravitational Potential Energy
Energy stored by an object by virtue of its position in the Earth’s gravitational field.
Ground State
The lowest energy state that can be occupied by an electron in an atom.
Hooke’s Law
The extension produced in an object is proportional to the force producing it, provided the elastic limit is not exceeded.
Elastic
Describes a material which will return to its original shape when the forces acting upon it are removed.
Elastic Limit
The value of stress beyond which an object will not return to its original dimensions.
Elastic Potential Energy
Energy stored in an extended or compressed material.
Electrical Resistance
The ratio of potential difference to current.
Electrolyte
An electrically conducting solution.
Electromagnetic Spectrum
A family of waves that travel through a vacuum at a speed of 3.0 x 10^8 ms-1
Electromotive Force
The energy gained per unit charge by charges passing through a supply.
Electronvolt
The energy gained by an electron travelling through a p.d of 1 volt.
Elementary Charge
The smallest unit of charge that a particle of object can have. It has a magnitude of 1.6 x 10^-19 C.
Emission Line Spectrum
A sharp and bright line of a unique wavelength seen in a spectrum.
Energy Level
The quantised energy states of an electron in an atom.
Force Constant
The ratio of force to extension for a spring or a wire.
Frequency
The number of oscillations of a particle per unit time.
Fundamental Frequency
The lowest frequency stationary wave for a particular system.
Gravitational Potential Energy
Energy stored by an object by virtue of its position in the Earth’s gravitational field.
Ground State
The lowest energy state that can be occupied by an electron in an atom.
Hooke’s Law
The extension produced in an object is proportional to the force producing it, provided the elastic limit is not exceeded.
Interference
The formation of points of cancellation and reinforcement where two coherent waves pass through each other.
Internal Resistance
The resistance of an e.m.f source.
Kilowatt-Hour
The energy transferred by a 1kW device in the time of 1 hour.
Kirchoff’s First Law
The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that same point.
Kirchoff’s Second Law
The sum of the e.m.f.s round a loop in a circuit is equal to the sum of the p.d.s in that same loop.
Mean Drift Velocity
The average speed of charged particles along the length of a conductor.
Moment
The moment of a force about a point is the magnitude of the force multiplied by the perpendicular distance of the point from the line of action of the force.
Newton
The amount of force produced when a mass of 1 kg is accelerated at a rate of 1 ms^-1.
Node
A point on a stationary wave with zero amplitude.
Number/Charge Density
The number of charged particles per unit volume.
Ohm’s Law
The current in a metallic conductor is directly proportional to the potential difference across its ends, providing temperature remains constant.
Path Difference
The differences in the distances travelled by two waves from coherent sources at a particular point.
Phase Difference
The fraction of a cycle between the oscillations of two particles, expressed in degrees.
Photon
A quantum of electromagnetic energy.
