Assam ASSEB HSLC NSQF Electronics and Hardware key terms

The electrical potential difference between two points that pushes charge through a circuit. Measured in volts (V) with a voltmeter connected in parallel across the points being tested.

The rate at which electric charge flows past a point in a circuit, measured in amperes (A). An ammeter or the current range of a multimeter measures it when wired in series.

The opposition a material offers to current flow, measured in ohms. Resistors use it deliberately to limit current or create voltage drops in a circuit.

The relationship stating voltage equals current multiplied by resistance (V = I x R). It lets a technician calculate any one of the three quantities when the other two are known.

A circuit where components connect end to end so the same current passes through each one. Total resistance adds up and a single break stops current everywhere.

A circuit where components connect across the same two nodes, so each receives the full supply voltage. Total resistance is lower than the smallest branch and one branch failing does not stop others.

A standard scheme where coloured bands on a resistor body encode its value and tolerance. Reading bands from the end nearest the edge gives digits, multiplier and tolerance.

A component that stores energy in an electric field between two plates separated by a dielectric. It blocks steady direct current while passing changing signals, and is rated by capacitance and working voltage.

A capacitor with a positive and negative terminal, such as an electrolytic type, that must be fitted the right way round. Reversing it can cause overheating, leakage or rupture.

A two-terminal semiconductor device that conducts easily in one direction and blocks the other. It is used for rectification, protection and signal steering in circuits.

A diode designed to operate safely in reverse breakdown at a specified voltage. It provides a stable reference or clamps voltage in regulator and protection circuits.

A three-terminal semiconductor device used to amplify signals or switch current. In bipolar types a small base current controls a larger collector current.

The permitted variation of a component's actual value from its marked value, usually given as a percentage. A wider tolerance means the part may differ more from its nominal rating.

Joining metal surfaces with a filler alloy melted at a temperature below the melting point of the parts. In electronics it forms both an electrical connection and a mechanical bond.

A chemical agent that removes oxide from metal surfaces and helps molten solder wet and bond to them. Rosin-based fluxes are common in electronics work.

A soldered connection where the solder has not properly wetted the pad or lead, giving a dull, rough surface and poor electrical contact. It often causes intermittent faults.

Removing solder from a joint to free a component or rework a connection. Tools include a desoldering pump, desoldering braid and hot-air rework station.

A spring-loaded vacuum tool that draws molten solder away from a joint. It is used with a soldering iron to clear pads and through-holes during desoldering.

A braid of fine copper strands that absorbs molten solder when pressed onto a joint with a hot iron. It is useful for cleaning pads and removing excess solder from fine-pitch work.

A printed circuit board: an insulating board with copper tracks that connect component pads according to a designed layout. It replaces most hand wiring in modern electronic products.

The protective lacquer layer on a printed circuit board that covers copper tracks and exposes only the pads to be soldered. It reduces bridging and protects against oxidation and contamination.

A test instrument that measures voltage, current, resistance and often continuity or diode drop. Correct range and probe placement are essential to avoid damage or wrong readings.

An instrument that displays how a signal's voltage changes over time on a screen. It reveals waveform shape, amplitude, frequency and timing faults that a meter cannot show.

A check that confirms a low-resistance path exists between two points, often signalled by a beep. It is done with power removed to trace wiring and find open connections.

A circuit that converts alternating current into direct current, typically using diodes. Half-wave types use one diode; bridge types use four to use both halves of the cycle.

A circuit or IC that holds an output voltage steady despite changes in input voltage or load current. Common types include fixed three-terminal linear regulators and switching regulators.

A store of chemical energy that delivers direct current at a rated voltage and capacity. Correct charging, polarity and disposal practices determine its life and safety.

A rechargeable battery type with high energy density that needs a dedicated charge controller to prevent overcharge, over-discharge and overheating. Punctured or swollen cells present a fire risk.

A basic digital circuit that produces an output determined by its inputs according to a fixed rule, such as AND, OR, NOT, NAND or NOR. Gates are combined to build decision logic.

A table listing every possible combination of inputs to a logic circuit alongside the resulting output. It is used to verify and design digital behaviour.

A number system using only the digits 0 and 1, each position representing a power of two. It matches the two voltage states that digital circuits use to represent data.

A single chip containing a processor, memory and programmable input/output peripherals. It runs a stored program to read sensors and control devices in embedded systems.

General-purpose input/output: configurable pins on a microcontroller that can be set by software as inputs or outputs. They connect the chip to switches, LEDs, relays and sensors.

The program and configuration stored in non-volatile memory on a microcontroller or embedded device. It defines how the hardware behaves and can usually be updated by flashing.

A switched-mode power supply that converts voltage by rapidly switching a transistor and storing energy in inductors and capacitors. It is efficient and compact but generates high-frequency noise.

Electrostatic discharge: a sudden transfer of static charge between bodies that can destroy or degrade semiconductor devices. Prevention uses wrist straps, mats, grounded benches and antistatic packaging.

A protective package, often metallised or dissipative, that shields sensitive components from static charge during storage and transport. Components should stay inside until fitted.

Connecting equipment or a person to earth or a common reference point so stray charge and fault current have a safe path. It is central to both electrical safety and ESD control.

Current that escapes from a live conductor to earth through a fault or insulation breakdown. A residual current device detects it and disconnects the supply to prevent shock.

A break in a current path that stops current flowing, giving no reading on a load and often infinite resistance across the break. It is found by continuity and voltage-drop testing.

An unintended low-resistance path between two points at different potentials, causing excessive current. It can blow fuses, damage components or start a fire if unprotected.

A deliberately weak link that melts and opens the circuit when current exceeds its rating. It protects wiring and components, and must be replaced with the same rating and type.