Key Terms: Letter E

E = mc²

Einstein’s equation that expresses the equivalence of energy (E) and mass (m), where c is the speed of light, showing that mass can be converted into energy and vice versa.

Efficiency

The ratio of useful energy output to total energy input, expressed as a percentage, measuring how effectively a system converts energy.

Einstein’s Mass Energy Equivalency

States that mass and energy are interchangeable, with energy being equal to mass multiplied by the square of the speed of light.

Electric Charge

A fundamental property of matter that causes it to experience a force when placed in an electric and magnetic field, existing in two types: positive and negative.

Electric Circuits

Closed loops or pathways through which electric current flows, typically involving a power source, conductors, and components like resistors, capacitors, and switches.

Electric Current

The flow of electric charge, typically carried by electrons, through a conductor or circuit, measured in amperes (A).

Electric Dipole

A system consisting of two equal and opposite charges separated by a small distance, creating an electric field with a characteristic dipole moment.

Electric Field

A region around a charged particle or object where other charged particles experience a force, with the field’s strength determined by the charge and distance from the source.

Electric Field Lines

Imaginary lines that represent the direction and strength of an electric field, pointing away from positive charges and toward negative charges, with the density of lines indicating the field’s intensity.

Electric Field Strength

The force per unit charge experienced by a test charge placed in an electric field, typically measured in newtons per coulomb (N/C).

Electric Motor

A device that converts electrical energy into mechanical energy through the interaction of magnetic fields and electric currents.

Electric Permittivity

A measure of how much a material can resist or permit the formation of an electric field within it, influencing the strength of electrostatic interactions.

Electric Potential

The amount of electric potential energy per unit charge at a specific point in an electric field, often measured in volts.

Electric Potential Energy

The energy stored in a system of charged particles due to their positions in an electric field.

Electrical Resistance

The opposition to the flow of electric current through a conductor, depending on the material, length, cross-sectional area, and temperature.

Electricity

The flow of electric charge, typically through a conductor, driven by differences in electric potential, and responsible for various physical phenomena such as electric current and electromagnetic fields.

Electromagnetic Field

A physical field produced by moving electric charges and changing magnetic fields, consisting of perpendicular electric and magnetic components that propagate as waves.

Electromagnetic Force

A fundamental force of nature that acts between charged particles, combining electric and magnetic forces and governed by Coulomb’s law and Maxwell’s equations.

Electromagnetic Induction

The process of generating an electric current or voltage in a conductor by changing the magnetic flux through it.

Electromagnetic Radiation

The transmission of energy through space in the form of oscillating electric and magnetic fields, traveling as waves at the speed of light.

Electromagnetic Spectrum

The complete range of electromagnetic waves arranged by frequency or wavelength, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Electromagnetic Wave

A self-propagating transverse wave consisting of oscillating electric and magnetic fields that travel through space at the speed of light.

Electric Flux

The measure of the electric field passing through a given surface, proportional to the field strength and the surface area perpendicular to the field.

Electric Force

The force exerted between charged objects due to their electric fields, described by Coulomb’s law.

Electric Generator

A device that converts mechanical energy into electrical energy by inducing an electromotive force (EMF) through electromagnetic induction.

Electron Energy Levels

Discrete regions around an atom’s nucleus where electrons are likely to be found, with each level corresponding to a specific amount of energy.

Electron Mobility

A measure of how quickly electrons can move through a conductive material when an electric field is applied.

Electron Transfer

The process by which an electron moves from one atom or molecule to another, often occurring in chemical reactions or electrical circuits.

Electrons

Negatively charged subatomic particles that orbit the nucleus of an atom and play a key role in chemical reactions and electrical conductivity.

Electrostatic Discharge

The rapid transfer of static electricity between two objects with different electrical potentials, often resulting in a spark or shock.

Emission Spectra

Refer to the wavelengths of light emitted by a substance when its atoms or molecules transition from a higher to a lower energy state, producing bright lines at specific wavelengths.

Endothermic Reaction

A chemical reaction that absorbs energy, typically in the form of heat, from its surroundings.

Energy Equivalent (MeV)

The amount of energy equivalent to a mass of 1 atomic mass unit, measured in mega-electron volts (MeV), and often used to express energy in nuclear reactions.

Energy Level Diagram

A graphical representation of the discrete energy levels of an atom or molecule, showing the transitions between these levels due to absorption or emission of energy.

Energy Stored in a Capacitor

The potential energy held in an electric field between its plates, calculated as E = ½ C V², where C is the capacitance and V is the voltage across the plates.

Entropy

A measure of the disorder or randomness of a system, with higher entropy indicating greater disorder and lower potential for energy to do work.

Exothermic Reaction

A chemical reaction that releases energy, typically in the form of heat, to its surroundings.

Experimental Design

Refers to the process of planning an experiment to test a hypothesis, including selecting variables, controls, and methods of data collection and analysis.

Electromagnetism

The branch of physics that deals with the study of electric and magnetic fields and their interactions, including phenomena such as electric currents, magnetic fields, and electromagnetic waves.

Electromotive Force

The energy per unit charge supplied by a source, such as a battery or generator, to drive an electric current through a circuit.

Electron Capture

A process in which an inner orbital electron is absorbed by a proton in the nucleus, transforming the proton into a neutron and emitting a neutrino.