Electric Current and Circuits - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on electric current, circuits, resistance, and electromotive force.

Electric field

The space around a charged particle where the electric force acts on other charges.

Charged particle

A particle or ion that carries electric charge (positive or negative).

Free electron

An electron that is not bound to an atom and can move to carry electric current.

Conductor

Material that allows electric charges to move through it easily (most metals are good conductors).

Insulator

Material that resists the flow of electric current (non-metals like glass, rubber).

Electron flow

Movement of electrons; in metals it is opposite to the direction of conventional current.

Conventional current

Direction of positive charge flow, opposite to electron flow in metals.

Current

Rate of flow of electric charge; I = Q/t; measured in amperes (A).

Potential difference

Work done to move a unit positive charge from one point to another; measured in volts (V).

Electromotive force (emf)

Potential difference across a source’s terminals when the circuit is open; energy supplied per unit charge.

Terminal voltage

Potential difference across a cell’s terminals when the circuit is closed and current flows.

Open circuit

A circuit with an incomplete path, so no current flows.

Closed circuit

A complete loop that allows current to flow.

Potential (electric potential)

Work needed to bring a unit positive charge from infinity to a point; unit volt (V).

Work (W)

Energy required to move charge; in voltage terms, W = V × Q.

Charge (Q)

Quantity of electricity; measured in coulombs (C).

Ohm’s law

I = V/R (or V = IR); current is proportional to voltage for a constant temperature conductor.

Resistance

Opposition to current flow; measured in ohms (Ω); depends on material, temperature, length, and cross-section.

Ohm (Ω)

Unit of resistance.

Conductance

Reciprocal of resistance; G = 1/R; measured in siemens (S).

Resistivity (ρ)

Intrinsic property of a material; R = ρL/A; unit is ohm-meters (Ω·m).

Series circuit

Components connected end-to-end; same current flows; total resistance is the sum of individual resistances.

Parallel circuit

Components connected across the same two nodes; currents divide; total resistance is less than any individual resistance.

Equivalent resistance

A single resistance that would produce the same current for a given circuit.

Ammeter

Device that measures current; connected in series; measured in amperes (A).

Voltmeter

Device that measures potential difference; connected in parallel; has high resistance.

Rheostat

Variable resistor used to adjust current; resistance changes to control current.

Battery

Source of emf composed of one or more cells; maintains potential difference in a circuit.

Cell

Single energy source with emf (ε); part of a battery.

Switch

Device to open or close a circuit; controls current flow.

Internal resistance

Opposition to current within a cell or battery (r); causes voltage drop V = IR across the cell.

Temperature coefficient of resistance (α)

Parameter describing how resistance changes with temperature; metals usually have positive α.

Ohmic conductor

Conductor that obeys Ohm’s law; linear I–V relationship with constant resistance.

Non-Ohmic conductor

Conductor that does not obey Ohm’s law; I–V relationship is non-linear.

Superconductor

Material with extremely low or zero resistance at very low temperatures.

Thermistor

Temperature-dependent resistor; resistance changes significantly with temperature.

Electron flow vs current direction

Current direction is defined as the direction positive charges would move; in metals, electrons move opposite to this direction.

Electric field

The space around a charged particle where the electric force acts on other charges.

Charged particle

A particle or ion that carries electric charge (positive or negative).

Free electron

An electron that is not bound to an atom and can move to carry electric current.

Conductor

Material that allows electric charges to move through it easily (most metals are good conductors).

Insulator

Material that resists the flow of electric current (non-metals like glass, rubber).

Electron flow

Movement of electrons; in metals it is opposite to the direction of conventional current.

Conventional current

Direction of positive charge flow, opposite to electron flow in metals.

Current

Rate of flow of electric charge; I = Q/t; measured in amperes (A).

Potential difference

Work done to move a unit positive charge from one point to another; measured in volts (V).

Electromotive force (emf)

Potential difference across a source’s terminals when the circuit is open; energy supplied per unit charge.

Terminal voltage

Potential difference across a cell’s terminals when the circuit is closed and current flows.

Open circuit

A circuit with an incomplete path, so no current flows.

Closed circuit

A complete loop that allows current to flow.

Potential (electric potential)

Work needed to bring a unit positive charge from infinity to a point; unit volt (V).

Work (W)

Energy required to move charge; in voltage terms, W = V  × Q.

Charge (Q)

Quantity of electricity; measured in coulombs (C).

Ohm’s law

I = V/R (or V = IR); current is proportional to voltage for a constant temperature conductor.

Resistance

Opposition to current flow; measured in ohms (Ω); depends on material, temperature, length, and cross-section.

Ohm (Ω)

Unit of resistance.

Conductance

Reciprocal of resistance; G = 1/R; measured in siemens (S).

Resistivity (ρ)

Intrinsic property of a material; R = ρL/A; unit is ohm-meters (Ω·m).

Series circuit

Components connected end-to-end; same current flows; total resistance is the sum of individual resistances.

Parallel circuit

Components connected across the same two nodes; currents divide; total resistance is less than any individual resistance.

Equivalent resistance

A single resistance that would produce the same current for a given circuit.

Ammeter

Device that measures current; connected in series; measured in amperes (A).

Voltmeter

Device that measures potential difference; connected in parallel; has high resistance.

Rheostat

Variable resistor used to adjust current; resistance changes to control current.

Battery

Source of emf composed of one or more cells; maintains potential difference in a circuit.

Cell

Single energy source with emf (ε); part of a battery.

Switch

Device to open or close a circuit; controls current flow.

Internal resistance

Opposition to current within a cell or battery (r); causes voltage drop V = IR across the cell.

Temperature coefficient of resistance (α)

Parameter describing how resistance changes with temperature; metals usually have positive α.

Ohmic conductor

Conductor that obeys Ohm’s law; linear I–V relationship with constant resistance.

Non-Ohmic conductor

Conductor that does not obey Ohm’s law; I–V relationship is non-linear.

Superconductor

Material with extremely low or zero resistance at very low temperatures.

Thermistor

Temperature-dependent resistor; resistance changes significantly with temperature.

Current direction is defined as the direction