Physics key words, t.2

Transducers

Devices that convert one form of energy into another form.

Voltage

An electromotive force or potential difference expressed in volts.

Electric potential

The amount of work needed to move a unit charge from a reference point to a specific point against an electric field.

Electromotive force

Energy per unit electric charge that is imparted by an energy source, such as an electric generator or a battery.

Potential energy

The energy that is stored in an object due to its position relative to some zero position.

Current

Characterizes the electric charge that passes through a cross section of a conductor per unit time.

Volts

Characterizes the potential energy in Joules per unit charge.

Ampere

One Ampere represents a flow of one coulomb of electrical charge per second.

Alternating current

An electric current which periodically reverses direction and changes its magnitude continuously with time.

Direct current

Electrical current which flows consistently in one direction.

Ohms

Electrical resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces in the conductor a current of one ampere.

Resistance

Measure of the opposition to current flow in an electrical circuit.

Posistor

Resistors with a positive temperature coefficient, which means that the resistance increases with increasing temperature.

Resistor

A passive electrical component with two terminals that are used for either limiting or regulating the flow of electric current in electrical circuits.

Thermistor

A type of resistor whose resistance is strongly dependent on temperature.

Electrons

Fundamental particles with negative electric charge that are found arranged in quantum mechanical orbits about neutral atoms.

Valence band

The band of electron orbitals that electrons can jump out of, moving into the conduction band when excited.

Conduction band

The band of electron orbitals that electrons can jump up into from the valence band when excited.

Metallic bond

Force that holds atoms together in a metallic substance.

Ionic bond

Linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound.

Covalent bond

Chemical bond that involves the sharing of electron pairs between atoms.

Conductor

Materials that permit electrons to flow freely from particle to particle.

Semiconductor

Materials which have a conductivity between conductors and non-conductors or insulators.

Insulator

A device used for isolating a circuit or equipment from a source of power.

Seebeck effect

Phenomenon in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances.

Peltier effect

The cooling of one junction and the heating of the other when electric current is maintained in a circuit of material consisting of two dissimilar conductors.

Thomson effect

The evolution or absorption of heat when electric current passes through a circuit composed of a single material that has a temperature difference along its length.

Thermocouple

A device that creates an electromotive force (EMF) when there is a temperature gradient along a conductor.

Signal

In signal processing, a function that conveys information about a phenomenon.

Energy

The capacity for doing work.

Sensor

A device which converts a physical property into an electrical property.

Electrode

An electrical conductor used to make contact with a nonmetallic part of a circuit.

Electrophoresis

A laboratory technique used to separate and analyze macromolecules based on their size and charge.1. Electric charge:The physical property of matter that causes it to experience a force when placed in an electromagnetic field.

Elementary charge

The electric charge carried by a single proton or a single electron.

Net charge

The overall charge of an atom, which can be positive (cation), negative (anion), or neutral (0).

Coulomb

The unit of electric charge, defined as the quantity of electricity transported in one second by a current of one ampere.

Coulomb's law

The law that quantifies the amount of force between two stationary, electrically charged particles.

Electric field

An electric property associated with each point in space when charge is present.

Electrical potential

The amount of work needed to move a unit charge from a reference point to a specific point against an electric field.

Potential difference

The difference in the amount of energy that charge carriers have between two points in a circuit.

Capacitor

A component that can store energy in the form of an electrical charge, producing a potential difference across its plates.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Isoelectric point

The pH at which a molecule or surface carries no net electrical charge.

pH

A quantitative measure of the acidity or basicity of a liquid solution.

Mobility of ion

The ratio of the average drift velocity of an ion to the electric field.

Velocity

The rate of change of an object's position with respect to a frame of reference.

Speed

The rate at which an object covers distance.

Emulsion

A mixture of two or more liquids in which one is present as droplets distributed throughout the other.

Suspension

A heterogeneous mixture in which solid particles are spread throughout a liquid without dissolving in it.

Stokes' Law

Describes the relationship between the frictional force of a sphere moving in a liquid and other quantities.

Piezoelectric effect

The ability of certain materials to generate an electric charge in response to applied mechanical stress.

Electrical impulse

The movement of electrons.

Electrophoresis

The motion of particles in a gel or fluid within an electric field.

Magnetic field

A vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials.

Magnetic flux

A measurement of the total magnetic field passing through a given area.

Magnetic flux density

The concentration of uniformly distributed flux per unit area.

Electromotive force (EMF)

The electric potential produced by either an electrochemical cell or changing magnetic field.

Faraday's law of electromagnetic induction

Any change in the magnetic field will induce a voltage and current in a circuit.

Induced EMF

The generation of a potential difference in a coil due to changes in magnetic flux.

Electromagnet

A magnet made by passing electric current through a coil surrounding a soft metal core.

Ferromagnetism

Substances that become strongly magnetized when placed in an external magnetic field.

Paramagnetism

Materials weakly attracted by an externally applied magnetic field, forming internal induced magnetic fields.

Diamagnetism

A weak form of magnetism induced by a change in the orbital motion of electrons due to an applied magnetic field.

Eddy currents

Localized electric currents induced in a conductor by a varying magnetic field.

Magnetic field of Earth

The magnetic field surrounding the Earth, caused by electrical currents in the molten iron core.

Solar wind

The continuous flow of charged particles from the sun throughout the solar system.

MRI

Magnetic Resonance Imaging, a medical procedure that uses a strong magnetic field and radio waves to create detailed images of organs and tissues within the body.1. ECG:Electrocardiogram - A test that measures the electrical activity of the heart.

Electric charge - A basic property of matter carried by some elementary particles that governs how the particles are affected by an electric or magnetic field.

Electric field - A region around a charged particle or object within which a force would be exerted on other charged particles or objects.

Electric dipole - Deals with the separation of the positive and negative charges found in any electromagnetic system.

Electric potential - The amount of work needed to move a unit charge from a reference point to a specific point against an electric field.

Capacitor - A component which has the ability or "capacity" to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery.

Electrocardiographic electrodes - Conductive pads attached to the body surface that measure the electrical potential difference between two corresponding locations of attachment.

Defibrillation - Devices that restore a normal heartbeat by sending an electric pulse or shock to the heart.

Pacemaker - Devices that send electrical pulses to help the heart beat at a normal rate and rhythm.

Waves - Disturbances that travel through a medium, transporting energy from one location to another without transporting matter.

Rhythm - Any regular recurring motion or symmetry.

Depolarization - A change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell.

Repolarization - A stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) ions along its electrochemical gradient.

Einthoven's triangle - An imaginary formation of three limb leads in a triangle that captures the heart bipotential difference between the vertices of an equilateral triangle.

Photocolorimetry - A method of determining the concentration of a liquid by measuring the wavelength with a spectrophotometer.

Absorption - The transfer of the energy of a wave to matter as the wave passes through it.

Absorbance - A measure of the quantity of light absorbed by a sample, also known as optical density.

Optical density - The measure of absorbance, or the transmission of light or other electromagnetic radiation by matter.

Transmittance - The proportion of incident light that moves all the way through a transparent or semi-transparent material.

Reflection - The change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

Scattering - A change in the direction of motion of a particle because of a collision with another particle.

Spectrum - The full range of all frequencies of electromagnetic radiation.

Light spectrum - The visible spectrum, the range of wavelengths of electromagnetic radiation which our eyes can see.

Ultraviolet - A form of radiation which is not visible to the human eye, in an invisible part of the electromagnetic spectrum.

Infrared - Light which has too high value of frequency for the human eye to see.

Color - The perception of different wavelengths of light.

Lambert-Beer's law - The intensity of light decreases as it passes through an object, and absorbance is proportional to the distance and concentration.

Atom - The smallest particle into which an element can be divided without losing its chemical identity, consisting of a central nucleus surrounded by electrons.1

Principal energy levels in an atom where electrons orbit around the nucleus.

Ground state

The lowest allowed energy state of an atom, molecule, or ion.

Excited state

A state in which a species has energy greater than the ground state.

Transition of electrons

A change of an electron from one energy level to another within an atom.

Emission spectrum

The spectrum of frequencies of electromagnetic radiation emitted when an atom or molecule transitions from a high energy state to a lower energy state.

Absorption spectrum

The spectrum of frequencies of electromagnetic radiation absorbed by a substance for composition analysis.