Physics Vocabulary

magnetic domain

A region within a ferromagnetic material which has individual atoms aligned in the same direction.

solenoid

A type of electromagnet where a long coil of wire generates an electric field.

electric generator

A device which converts mechanical energy into electrical energy.

electric motor

A device which converts electrical energy into mechanical energy.

electromagnetic induction

When a current is produced because of a voltage production due to the magnetic field changing.

magnetic flux

The measure of the number of electric/magnetic field lines passing through a surface.

transformer

A device which transfers electric energy from one alternating-current circuit to one or more other circuits. In this process, the voltage is either increased or decreased.

conventional current

Indicates which direction positive particles would flow in a circuit.

electron flow

Indicates which direction electrons will flow in a circuit.

true north

A fixed point on the "top" of Earth. Also called the "north pole".

magnetic north

A non-fixed point usually near the "bottom" of Earth which has magnetic force.

true south

A fixed point on the "bottom" of Earth. Also called the "south pole".

magnetic south

A non-fixed point usually near the "top" of Earth which has magnetic force.

uniform magnetic field

A region where the magnetic field strength and direction are the same at all points.

ferromagnetic

When materials become strongly magnetized when put into a magnetic field.

paramagnetic

When materials become weakly magnetized when put into a magnetic field.

diamagnetic

Materials considered non-magnetic.

potential difference

A different term for voltage.

lenz's law

A law stating induced current in a circuit always flows in a direction that opposes the change in the magnetic flux which produced it.

spherical aberration

In mirrors, light reflected at the outside of the mirror is distorted more.

chromatic aberration

In lenses, light reflected at the outside of the lens is distorted more.

compound microscope

A microscope which uses two or more lenses to magnify objects.

critical angle

The largest angle of incidence at which light would not be refracted through a second medium with a higher index of refraction.

dispersion

When white light spreads out into its full spectrum of wavelengths (colors).

index of refraction

Determines the speed of light through a medium. This has no unit.

focal length

A distance used in lens and mirror diagrams. Light will reflect or refract towards this point.

law of reflection

A law which states the angle of incidence is always equal to the angle of reflection.

law of refraction

A law which states light will "bend" away from the normal when traveling from a higher index of refraction to a lower index of refraction. This also applies vice versa ("bend" toward the normal when traveling to a higher index of refraction).

real image

An image which is always flipped and can be projected. Rays of light actually meet.

virtual image

An image which is always upright and cannot be projected. Rays of light appear to meet.

total internal reflection

If the incident angle in a medium is greater than the critical angle, all light will be reflected back within the medium.

refraction

The bending of light waves as they travel through different mediums.

specular reflection

Light reflects by the law of reflection (a smooth surface). In other words, you would be able to see yourself clearly in the reflection.

diffuse reflection

Light reflects in all directions (a rough surface). In other words, you would not be able to see yourself in the reflection, yet light is still being reflected.

frequency

The number of cycles of a wave that occur within a unit of time. In other words, the amount of periods which pass in a given time.

wavelength

Distance from trough-to-trough or crest-to-crest on a wave.

converge

When light rays meet or cross.

diverge

When light rays spread apart.

convex mirrors

A mirror with a reflective surface curving outwards. It can create small virtual images.

convex lenses

A lens which curves outwards on both sides and is thicker in the center than on its outer edges. It can create any real image and large virtual images.

concave mirrors

A mirror with a reflective surface curving inwards. It can create any real images and large virtual images.

concave lenses

A lens which curves inwards on both sides and is thicker on its outer edges than in the center. It can create smaller virtual images.

center of curvature

The theoretical center of a spherical mirror (all points are the same distance away). It is equal to two times the focal length.

optical center

The center of a lens.

principal axis

A nonexistent line perpendicular to the surface and passing through the optical center of a lens.

focus

The point on the principal axis where light rays converge after passing through a lens.

absolute zero

Zero degrees kelvin, no movement of molecules.

critical point

The point where a substance at any pressure turns to gas.

heat

The movement of thermal energy.

thermal energy

The kinetic energy of molecules or atoms which is related to temperature.

internal energy

The combination of kinetic and potential energy.

latent heat of fusion

Heat required to phase change between solid and liquid. (Temperature remains constant.)

latent heat of vaporization

Heat required to phase change between liquid and gas. (Temperature remains constant.)

mole

A measure of 6.02 x 10^23 of any substance.

specific heat

The amount of heat required to heat 1 gram of a substance 1 celsius degree.

sublimation

When solid phase changes to a gas.

deposition

When gas phase changes to a solid.

temperature

Average kinetic energy of a system or molecule.

thermal conductivity

The ability of a material to conduct and transfer heat.

triple point

The point where a substance can exist as a solid, liquid, and gas at equilibrium.

vapor

A gas that is below the critical point.

convection

A transfer of heat when heat goes from hot to cold through currents.

radiation

A transfer of heat through electromagnetic waves.

conduction

Heat transfer through touching objects.

calorie

The amount of energy it takes to heat up 1 gram of water 1 celsius degree.

kilocalorie, dietary calorie

The amount of heat needed to heat up 1 kilogram of water 1 celsius degree. Also equal to 1000x a calorie.

thermal equilibrium

When there is no transfer of thermal energy, therefore no heat.

heat engine

A system which relies on heat energy to produce work.

entropy

The inability to do work.

adiabatic

No transfer of heat energy. ΔU = W.

isothermic

Constant temperature. Q = -W.

isobaric

Constant pressure. ΔU = Q + W.

isometric

Constant volume. ΔU = Q.

carnot cycle

An ideal cycle which has the maximum efficiency for a heat engine. This is entirely hypothetical and is impossible to create.

cyclic process

A process which returns back to where it started.

isochoric

Constant temperature, another word for "isothermic".

conductor

Easily transfers electrons. The electric field inside the object is zero.

insulator

Does not transfer electrons. The electric field is distributed throughout the object.

grounded

Touching a large object with a neutral charge, such as the Earth.

electrostatic equilibrium

When there is no movement of charge.

charging by friction

When two substances are rubbed together and electrons rub off from one substance to another.

charging by conduction

When a charged substance touches another substance and transfers its electrons. The charges between the two objects will then be equal.

charging by induction

When two objects are brought close to each other, but not touching. This causes a temporary polarization.

capacitor

Two conductors separated by an insulator.

dielectric

An insulator, specifically an insulator in a capacitor.

electron volt

A unit of energy of the work done to accelerate an electron through a potential difference of one volt.

parallel circuit

A circuit which has more than one path for current to flow through.

series circuit

A circuit which has a single path for current to flow through.

voltage

The pressure from a circuit's power source which pushes electrons through the circuit.

direct current

Current which always flows in one direction.

alternating current

Current which changes direction continuously.

short circuit

A situation where a circuit creates an unintended path. This causes electric current to flow through with no resistance and does not go to other branches of the circuit.

equivalent resistance

The single resistance value which would replace multiple resistors in a circuit network.