4) Physics and Math

Aberration

Visual alterations as the result of an imperfect optical device; may be chromatic or spherical.

Absolute pressure

The actual pressure at a given depth in a fluid, including both ambient pressure at the surface and the pressure associated with increased depth in the fluid; also called hydrostatic pressure.

Absolute zero

The theoretically coldest temperature at which all atomic movements would halt (0 K).

Acceleration

The rate of change in the velocity of an object; related to force through mass and measured in m/s2.

Accuracy

The tendency for data to represent the true answer; also known as validity.

Adhesion

The intermolecular force between molecules of a liquid and molecules of another substance.

Adiabatic

A thermodynamic process that occurs with no heat exchange.

Air resistance

The resistance that opposes the motion of a falling object.

Algebraic system

A method for determining the values of variables that are the same in two or more equations by relating them to each other.

α-particle

A helium nucleus (4:2He) emitted during alpha decay.

Alternating current (AC)

In circuits, a pattern of current flow that changes direction periodically.

Ammeter

A device used to measure current within a circuit.

Amplitude

The maximum displacement from the equilibrium point during wave or oscillatory motion.

Antinode

A point of maximum displacement in a standing wave.

Archimedes' principle

States that a body immersed in a volume of fluid experiences a buoyant force equal to the weight of the displaced fluid.

Atomic absorption

Process in which an electron jumps from a lower to a higher energy orbit by absorbing a photon of light.

Atomic emission

Process by which an electron falls from a higher to a lower energy level and emits a photon of light.

Atomic number

The number of protons in the nucleus of a given element.

Attenuation

The loss of energy of a propagating wave as a result of nonconservative forces; also known as damping.

Autonomy

The ethical principle that states that individuals have the right to make decisions about their own healthcare.

Beat frequency

The difference between the frequencies of two interacting sound waves.

Beneficence

The ethical principle that states that practitioners should always act in their patients' best interests; in research ethics, also states that a research project should create a net positive change for both the study population and general population.

β-particle

An electron emitted during β- decay, or a positron emitted during β+ decay.

Bernoulli's equation

An equation that relates static and dynamic pressure for a fluid to the pressure exerted on the walls of a tube and the speed of the fluid.

Bias

A result of flaws in the data collection phase of an experimental or observational study that typically skews data within a study.

Bimodal distribution

A distribution of data with two peaks and a valley in between them.

Blackbody

An ideal absorber of all wavelengths of light.

Blinding

Withholding information about a research subject's group assignment from the subject or evaluator to remove some potential bias from the results.

Boiling point

The temperature at which the vapor pressure of a liquid equals the ambient (incident) pressure, usually atmospheric pressure; the temperature at which the liquid boils.

Boundary layer

A region of laminar flow in an otherwise turbulent system that occurs at the very edges of the vessel.

Box-and-whisker plot

A visual representation of the range of data, quartiles, and the interquartile range; may contain outliers as separate points.

Buoyancy

The upward force that results from immersion in a fluid; described by Archimedes' principle.

Capacitance

A measure of the ability of a capacitor to store charge; the magnitude of the charge on one plate divided by the potential difference between the plates; measured in farads (F).

Capacitor

Two conducting surfaces that store charges of equal magnitude but opposite sign when connected to a voltage source.

Case-Control Study

An observational study that starts by identifying subjects with a given outcome, then looks for correlations to specific exposures within the group.

Causation

A relationship between two variables in which one (at least partially) depends on the other in order to occur.

Center of gravity

A point such that the entire force of gravity acting on an object can be thought of as acting at that point.

Center of mass

The point that acts as if the entire mass of an object was concentrated at that point.

Centripetal acceleration

The acceleration of an object that travels in a circle; it is always directed toward the center of the circle if the object is in uniform circular motion.

Centripetal force

The force responsible for centripetal acceleration; usually a result of gravity, tension, or a normal force.

Charges

Entities that can influence the environment through electrostatic forces or be influenced by electrostatic forces, measured in coulombs (C).

Chromatic aberration

A dispersive effect within a spherical lens.

Circular motion

A form of motion that occurs when forces cause an object to move in a circular pathway.

Cohesion

The intermolecular forces experienced between the molecules of a liquid.

Cohort study

An observational study in which subjects are sorted into groups based on different exposures, and then assessed at various intervals to determine outcome.

Concave

A surface that has a similar curvature to the interior of a sphere.

Condensation

The phase transition from a gas to a liquid.

Conductance

In the transfer of charge, the degree to which an object conducts electricity. Conductance can be metallic or electrolytic.

Conduction

In thermodynamics, the transfer of heat by physical motion of a fluid over a material.

Conduction pathway

a route for current to take through a resistor.

Conductor

A material that allows the free movement of electrical charge; one with very low or zero resistance.

Confidence

A statistical indicator of the likelihood that acquired results did not occur by random chance; equal to 1 - α.

Confounding

An error that results when a causal variable is associated with two other variables in a study but is not accounted for; may falsely indicate that the two variables are associated.

Conservative force

A force that does not cause energy to be dissipated from a system, such as gravity, electrostatic forces, and springs (approximately conservative); pathway independent and associated with a potential energy function.

Control

A set of experimental conditions meant to ensure that the results of the experimental group are a result of the intervention.

Convection

Heat transfer as a result of bulk flow of a fluid over an object.

Converging

The tendency to move parallel light rays toward one another; concave mirrors and convex lenses converge parallel light to a focal point.

Convex

A surface that has a similar curvature to the exterior of a sphere.

Correlation

The degree to which two variables have a relationship with one another.

Correlation coefficient

A numerical value between -1 and +1 that indicates how strong a relationship is between two variables.

Coulomb's law

Relates the electrostatic force between two charged particles to their charges and the distance between them.

Critical angle

The angle above which any incident light will undergo total internal reflection; occurs when light is moving from a material with a higher refractive index to one with a lower refractive index.

Critical speed

The speed above which flow of a fluid will be turbulent.

Cross-sectional study

An observational study in which patients are categorized into different groups at the same point in time.

Current

The orderly movement of charge, often in a circuit; measured by convention as the direction that positive charge would flow within the circuit, and measured in ampères (A).

Decay constant

The proportionality constant between the rate at which radioactive nuclei decay and the number of radioactive nuclei remaining.

Density

A measure of mass per unit volume; useful for buoyancy calculations and usually measured in

g/cm3, kg/m3, or g/mL.

Dependent variable

The measured or observed variable in an experiment that is affected by manipulations of the independent variable.

Detection bias

An error in data collection that results from the tendency to look more carefully for certain outcomes because a known association with that outcome exists.

Diamagnetic material

A material made of atoms with no unpaired electrons that have no net magnetic field.

Dielectric material

An insulating material used to increase capacitance.

Diffraction

The spreading or bending of light rays.

Dipole moment

In electrostatics calculations, the product of charge and separation distance.

Direct current (DC)

In circuits, a pattern of current in which charge flows in only one direction.

Direct relationships

A relationship in which increasing one variable proportionately increases the other.

Dispersion

The separation of light into its component wavelengths when passing through a medium, such as a prism.

Displacement

The vector representing the straight-line distance and direction from an initial point; not necessarily equal to total distance traveled, and measured in meters.

Diverging

The tendency to move parallel light rays away from one another; convex mirrors and concave lenses diverge parallel light rays from a focal point.

Doppler effect

Quantifies the perceived change in frequency of sound due to relative movement between the source and detector (observer).

Double-blind experiment

Experiment in which both the assessor and the subject do not know the subject's group.

Dynamics

In kinematics and dynamics, the study of forces and torques.

Efficiency

In machines, the ratio of useful work output compared to work input.

Electric dipole

A separation of equal and opposite charge by a small distance; can be seen in polar molecules.

Electric field

A region generated by an electric charge or multiple charges that can exert a force on another charge brought into the field; measured in N/C.

Electric meters

Devices used to measure circuit quantities like current, potential difference, or resistance.

Electric potential

A measure of electric potential energy per unit charge, given in volts (V); differences in electric potential (voltage) also drive current as the electromotive force in a circuit.

Electric potential energy

A form of potential energy that is dependent on the relative position of one charge with respect to another charge or to a collection of charges.

Electromagnetic radiation

A form of energy composed of oscillating electric and magnetic fields perpendicular to each other and perpendicular to the direction of propagation; includes visible light and other types of transverse waves, and can travel through a vacuum.

Electromagnetic spectrum

The full range of frequencies and wavelengths of electromagnetic waves.

Electromotive force

The difference in electric potential (voltage) that drives current in a circuit or battery.

Electron

A subatomic particle that remains outside the nucleus and carries a single negative charge.

Electron capture

A process in which an unstable atom absorbs an inner electron that combines with a proton to form a neutron, while releasing a neutrino.

Electrostatics

The study of stationary charges and the forces that are created by (and act upon) these charges.

Energy

The capacity to do work or transfer heat, measured in joules (J).

Entropy

A statistical measure of the distribution of unusable energy or heat; randomness introduced to a system, measured in J/g⋅K.

Equilibrium

The state at which the net torque or net force is equal to zero, such that there is no acceleration.

Equipoise

The state of not knowing whether there is a difference between two interventions; ethically necessary for comparative study of the interventions.

Equipotential lines

Regions within an electric field with equal electric potential; movement from one point on these lines to another causes no change in the energy of the system.

Excited state

Describes an atom in which an electron occupies an energy state above the minimum energy (ground) state.