Electrical Systems and Control

Vocabulary flashcards covering electrical components, circuits in series and parallel, logic switch configurations, Ohm's law, semiconductor diodes, transistors, sensors, and capacitors.

Resistor

A component that limits or regulates the flow of electrical current in a circuit, and can also be used to provide a specific voltage for a device such as a transistor.

Switch

A control component used to make or break an electric circuit, turning current on or off in an electrical appliance.

Light Emitting Diode (LED)

A semiconductor diode that produces light when current flows through it in one direction, converting electrical voltage into light while typically drawing around $20\,mA$.

Buzzer

An output device that creates an audible tone in the form of a buzzing or beeping sound when the circuit is complete and the switch is turned on.

Transistor

A three-terminal semiconductor device that regulates or controls current or voltage, or amplifies electrical current to produce a higher output current.

Cells in Series

An arrangement where cells are connected end-to-end with the positive pole of one connected to the negative pole of the next, providing only one path so the total voltage is the sum of the individual voltages ($1,5\,V + 1,5\,V + 1,5\,V = 4,5\,V$).

Cells in Parallel

An arrangement where all positive poles connect together and all negative poles connect together, providing multiple current paths so the total voltage equals that of a single cell ($1,5\,V$).

Lamps in Series

A circuit connection where the current passing through each lamp is identical, and the total circuit voltage drop equals the sum of the individual voltage drops across all lamps.

Lamps in Parallel

A circuit configuration where the applied voltage is identical across every lamp branch, and the total circuit current equals the sum of branch currents ($I_t = I_1 + I_2 + I_3$).

Switches in Series (AND function)

A circuit arrangement where two or more switches share the same path; both switches must be closed simultaneously for the circuit to complete and the lamp to glow.

Switches in Parallel (OR function)

A circuit arrangement where current can travel through alternate branches, producing an output of $1$ (lamp turns on) whenever switch A or switch B is closed.

Diode

A polar two-terminal electronic control component that allows electric current to flow in one direction only.

Forward Bias

The operating state of a diode where the positive anode is connected to a higher voltage than the negative cathode, allowing current to flow across the diode.

Reverse Bias

The condition where the cathode of a diode is at a higher voltage than the anode, preventing the diode from conducting electricity.

Electrical Resistance

The ability of a material or component to oppose and reduce the flow of electric current, measured in ohms ($\Omega$).

Resistor Tolerance

The accuracy rating of a resistor, indicated by the fourth colour band on a 4-band resistor and expressed as a percentage deviation from its nominal value.

Ohm's Law

The quantitative principle stating that, for a constant resistance, the current in a circuit is directly proportional to the applied voltage ($V = I \times R$).

Ammeter

An instrument with very low internal resistance connected in series to measure electric current in amperes ($A$).

NPN Transistor Terminals

The three conducting pins of an NPN transistor consisting of the Base (receives input control signal), Collector (connects to the load/positive supply), and Emitter (connects to ground/negative supply).

Pole (Switch)

The number of separate circuits that a manual switch makes or breaks.

Throw (Switch)

The number of positions to which each pole of a manual switch can be switched.

SPST Switch

Single Pole Single Throw switch; a basic manual switch that controls a single ON/OFF connection for one circuit.

SPDT Switch

Single Pole Double Throw switch; a single-pole changeover switch that directs current from one common terminal between two alternative circuits.

DPST Switch

Double Pole Single Throw switch; a switch that simultaneously opens or closes two independent circuits with a single ON/OFF action.

DPDT Switch

Double Pole Double Throw switch; a double-pole changeover switch that simultaneously switches two separate poles between two sets of output contacts.

Light-Dependent Resistor (LDR)

A non-polar input sensor whose electrical resistance decreases in the presence of light and increases in darkness.

Thermistor

A heat-sensitive resistor used as an input sensor that alters its electrical resistance in response to changes in ambient temperature.

Positive Temperature Coefficient ($+t$) Thermistor

A type of thermistor whose electrical resistance increases as temperature rises.

Negative Temperature Coefficient ($-t$) Thermistor

A type of thermistor whose electrical resistance decreases as temperature rises, permitting more current to flow.

Capacitor

An electronic control component that stores electrical energy when a circuit is turned on and discharges it back into the circuit to smooth current flow.

Non-polarised Capacitor

A non-electrolytic capacitor having a low capacitance value that can be connected in either orientation without malfunctioning.

Polarised Capacitor

An electrolytic capacitor with high capacitance that features distinct positive (+$) and negative (-$$) leads which must be connected in the correct orientation.