TASC Electronics and Advanced Technologies Level 3 key terms

The relationship stating that voltage across a resistor equals current through it multiplied by its resistance. It lets you calculate any one of the three quantities when the other two are known.

The principle that the algebraic sum of all voltage drops and rises around any closed loop in a circuit equals zero, reflecting conservation of energy.

The principle that the total current entering a junction equals the total current leaving it, because charge cannot accumulate at a node.

The ability of a component to store electric charge per unit of applied voltage, measured in farads. Capacitors oppose changes in voltage and block steady direct current.

The property of a coil that opposes changes in current by storing energy in a magnetic field, measured in henries.

The frequency-dependent opposition a capacitor or inductor presents to alternating current, measured in ohms but dissipating no real power.

The total opposition to alternating current from resistance plus reactance, expressed as a complex quantity with magnitude and phase angle in ohms.

The condition in which a circuit's inductive and capacitive reactances cancel, leaving only resistance and producing maximum or minimum response at a particular frequency.

The deliberate addition of impurity atoms to pure silicon to create free electrons (n-type) or holes (p-type), giving the material controlled conductivity.

The boundary formed where p-type and n-type semiconductor regions meet, creating a depletion zone that allows current mainly in one direction.

A two-terminal semiconductor device that conducts readily in one direction and blocks current in the other, used for rectification and protection.

Setting the steady direct-current voltages and currents at a transistor's terminals so it operates in the desired region of its characteristic curves.

The specific combination of collector current and collector-emitter voltage where a transistor sits when no signal is applied, also called the quiescent point.

A high-gain differential voltage amplifier, usually integrated, whose behaviour is set by external feedback components to perform math and signal functions.

Returning a fraction of an amplifier's output to its inverting input in opposition to the input, which stabilises gain, widens bandwidth and reduces distortion.

A circuit that compares two input voltages and switches its output between two states depending on which input is higher.

A basic digital circuit that performs a Boolean operation such as AND, OR, NOT or XOR on one or more binary inputs to produce an output.

A chart listing every possible combination of binary inputs to a logic circuit alongside the resulting output, used to verify behaviour.

A set of rules for manipulating binary variables using operations like AND, OR and NOT, used to simplify digital logic expressions before implementation.

A circuit that samples a continuous analog voltage and produces a proportional binary number, characterised by resolution and sampling rate.

The smallest voltage change a converter can distinguish, set by its bit count; an n-bit converter divides the reference range into 2^n steps.

The unavoidable difference between a true analog value and the nearest digital step that represents it, bounded by half of one least significant bit.

A technique that varies the on-time fraction of a fixed-frequency square wave to control average power delivered to a load such as a motor or lamp.

The proportion of one period during which a pulse or signal is in its active state, usually expressed as a percentage.

A signal that causes a processor to pause its current program, run a short service routine, then resume where it stopped.

A hardware counter that resets the processor if firmware fails to refresh it within a set time, recovering systems from lock-ups.

A computing system whose correctness depends on producing outputs within defined deadlines as well as producing the right values.

A device that detects a physical quantity such as temperature, light or pressure and converts it into an electrical signal that a system can read.

Any device that converts one form of energy into another; sensors and actuators are both examples of transducers.

A device that converts an electrical control signal into physical motion or action, such as a motor, solenoid or hydraulic valve.

Processing a raw sensor output by amplifying, filtering, isolating or linearising it so a controller or converter can use it reliably.

A circuit, usually built from diodes, that converts alternating current into pulsating direct current.

The small residual alternating voltage superimposed on a direct-current supply output after rectification and filtering.

A supply that rapidly switches a semiconductor on and off to transfer energy through an inductor or transformer, achieving high efficiency.

The ratio of real power to apparent power in an alternating-current circuit, ranging from zero to one and affected by phase shift and distortion.

Varying a property of a carrier wave, such as amplitude, frequency or phase, to carry information.

The range of frequencies a channel or circuit can carry or pass effectively, usually measured between the half-power points.

The ratio of desired signal power to unwanted noise power at a point in a system, usually stated in decibels.

A conductive enclosure or braid that blocks electric and magnetic fields to keep interference out of, or inside, a circuit or cable.

A control method that measures the actual output and compares it with the desired value, adjusting the input to reduce the error.

The target value that a control system is instructed to maintain for the measured variable.

The difference between the setpoint and the measured process value, which drives the controller's corrective action.

A control strategy that combines a term proportional to the current error, one summed over time and one based on the error's rate of change.

A test instrument that displays a voltage waveform against time on a screen, letting you measure amplitude, period, rise time and phase.

A handheld instrument that measures voltage, current, resistance and often continuity or other quantities, selectable by a rotary switch.

Connecting a circuit or chassis to the earth or a common reference point to provide safety and a stable voltage reference.

A protective switch that trips when it detects a small imbalance between live and neutral currents, indicating leakage to earth.

A safety procedure that isolates energy sources and attaches warning tags so equipment cannot be re-energised while someone works on it.