Current Electricity

Static Electricity

Movement of electrons in an uncontrolled way

Current Electricity

Controlled flow of electrons through a conductor

Direct Current (DC)

Flow of electrons in one direction through an electric circuit; produced by an electric cell to power small devices

Alternating Current (AC)

Flow of electrons that alternate in direction through an electric circuit;(produced by generating stations/wall outlets to power lights and large devices)

Electric Circuit

Closed, continuous loop of conductive material that allows electricity to flow from a source to a device and back again

Energy Source

The part of a circuit that provides electricity (e.g., battery or generating station)

Load

Device that transforms electrical energy into other usable forms of energy (e.g., heater, lamps, fan)

Conducting Wires

Joins the parts of an electric circuit together, providing a path for electrons

Switch

Device that controls flow in an electric circuit by opening or closing the loop

Open Switch

A switch that is off, creating a break in the connection so no electricity can flow

Closed Circuit

A switch that is on, making the loop continuous so electricity flows

Voltage (Potential Difference)

The difference in energy that pushes charges through a circuit; measured in Volts (V)

Voltmeter

Device used to measure potential difference (voltage); must be connected in parallel with a load or energy source

Current (I)

The flow of electrons; measured in Amperes (A)

Ammeter

Device used to measure electric current at a specific point; must be connected in series with a load

Resistance (R)

How much a material opposes current flow; measured in Ohms (Ω)

Ohmmeter

Device used to measure resistance; must be connected in parallel like a voltmeter

Resistance - Material

Conductors have lower resistance than insulators

Resistance - Thickness

Thick wires have less resistance than thinner ones because electrons flow more freely

Resistance - Length

The longer the wire, the more resistance as electrons have farther to travel

Resistance - Temperature

Resistance increases with temperature because atoms are more active and vibrate, reducing electron flow

Insulators

Materials with high resistance because the atoms are tightly bound to electrons

Resistor

A device that reduces the flow of energy

Kirchhoff’s Law (Series)

Current is the same everywhere ( It= I1 = I2 = I3); Voltage is the sum of parts (Vt = V1+V2+V3)

Kirchhoff’s Law (Parallel)

Current is the sum of parts ( It= I1 + I2 +I3); Voltage is the same everywhere (Vt = V1= V2 = V3)

Ohm's Law

States that the voltage between two points in a conductor is directly related to the current flowing through it

Ohmic Resistors

Loads that do not change resistance with temperature; results in a straight linear graph

Non-ohmic Resistors

Resistance changes as voltage or temperature changes; results in an exponential graph