Karnataka KSEAB SSLC NSQF Electronics and Hardware key terms

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

The rate at which electric charge flows past a point in a circuit, measured in amperes. An ammeter is connected in series so the current passes through it.

The opposition a material offers to current flow, measured in ohms. Higher resistance limits current for a given applied voltage and converts electrical energy into heat.

The relationship stating that voltage equals current multiplied by resistance (V = I x R). It allows any one quantity to be calculated when the other two are known.

A connection in which components form a single path so the same current flows through each. Total resistance is the sum of individual resistances and a break stops all current.

A connection in which components share the same two nodes, so voltage across each is equal while current divides between branches. Total resistance is always lower than the smallest branch resistance.

A passive component made to provide a specific resistance, used to limit current, divide voltage or set bias. Its value is shown by a colour code and its power rating in watts.

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 stores charge measured in farads.

A two-terminal semiconductor device that conducts easily in one direction (forward bias) and blocks the other (reverse bias). Used for rectification, protection and signal clamping.

A light-emitting diode that produces light when forward biased and current flows through it. It must always be used with a series resistor to limit current and prevent damage.

A three-terminal semiconductor device used as a switch or amplifier. A small base current controls a larger collector current, allowing weak signals to control heavier loads.

A circuit, usually built from diodes, that converts alternating current into pulsating direct current. A bridge rectifier uses four diodes to give full-wave output.

An electromagnetic switch in which a coil moves contacts to open or close a separate circuit. It lets a low-power control signal switch a higher-power load safely.

Two resistors connected in series across a supply so that the voltage across one is a fixed fraction of the total. Used to give a reference or reduced voltage to a circuit.

The standard banding system on resistors and some capacitors that encodes value and tolerance. Reading from the band nearest the end, bands give digits, multiplier and tolerance.

The permitted variation of a component's value from its marked nominal value, expressed as a percentage. A 100 ohm resistor with 5 percent tolerance may lie between 95 and 105 ohms.

A joining process in which a filler alloy is melted to bond metal surfaces without melting the parts themselves. In electronics, tin-lead or lead-free solder with flux forms the joint.

A chemical agent in solder or applied separately that removes oxide from metal surfaces and helps molten solder wet them. Residue may need cleaning to avoid corrosion or leakage.

The spreading of molten solder over a clean, hot metal surface to form a continuous metallic bond. Poor wetting produces a rounded, blobby joint that conducts unreliably.

A solder connection that looks dull, granular or ball-shaped because the surfaces did not wet properly. It gives high resistance or intermittent contact and must be reworked.

The ease with which a surface accepts solder to form a sound joint. It depends on cleanliness, absence of oxide, correct temperature and adequate flux activity.

A joint formed when the soldering iron is too cool or the part moved while cooling, leaving a rough, poorly bonded connection. Often visually similar to a dry joint.

A printed circuit board: an insulating board with copper tracks that connect components and replace most point-to-point wiring. It provides mechanical support and repeatable connections.

An assembly method in which component leads pass through holes in the board and are soldered on the opposite side. Joints are usually stronger and easier to inspect than surface-mount joints.

Surface-mount device: a component designed to sit directly on board pads and be soldered without leads passing through the board. It allows smaller boards and automated assembly.

The copper pad pattern on a board that matches a particular component's lead or terminal layout. A wrong footprint makes the part impossible to fit or solder correctly.

The copper conductor on a printed circuit board that carries current between pads and components. Width must be chosen to carry the expected current without overheating.

A general-purpose instrument that measures voltage, current, resistance and often continuity. Correct function and range must be selected before probing to avoid damage or wrong readings.

A test mode or instrument that gives a sound or indication when a very low resistance path exists. Used to check fuses, tracks, switches and cable conductors for breaks.

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

The number of complete cycles of a periodic signal in one second, measured in hertz. It is the reciprocal of the period and is read from a counter or oscilloscope.

The proportion of one period during which a pulse signal is high, usually expressed as a percentage. It affects average power delivered to a load such as a motor or lamp.

A basic digital circuit that produces a defined output from one or more binary inputs according to a truth table. Common types are AND, OR, NOT, NAND, NOR and XOR.

A table listing every possible combination of inputs to a logic circuit and the resulting output. It is used to verify gate behaviour and to design or simplify circuits.

A system of algebra using the values true and false combined with AND, OR and NOT operations. It allows logic circuits to be expressed as equations and simplified.

A single integrated circuit containing a processor, memory and input/output peripherals that runs a stored program. It controls hardware such as sensors, motors and displays in embedded systems.

General-purpose input/output: configurable pins on a microcontroller that can be set as digital inputs or outputs under program control. They connect the controller to switches, LEDs and drivers.

Pulse-width modulation: rapidly switching a digital output on and off with a variable duty cycle to control average power. Used to dim LEDs and vary motor speed.

The program and configuration stored in a device's non-volatile memory that controls its operation. It can usually be updated to fix faults or add features.

Electrostatic discharge: a sudden transfer of static charge between bodies at different potentials. It can destroy or degrade semiconductor devices, so grounded wrist straps and mats are used.

Connecting equipment or a person to earth or a common reference so static charge drains away safely. It also provides a return path and protects against electric shock.

A conductive or dissipative work surface connected to ground that safely bleeds static charge from components and tools. It is used with a wrist strap at ESD-protected benches.

Personal protective equipment: items such as safety glasses, gloves and footwear worn to reduce injury risk. It is the last line of defence after eliminating or controlling hazards.

Vapour and fine particles released from flux when soldering, which can irritate eyes and airways. Local extraction or fume extraction and good ventilation are required at the bench.

A systematic process of locating a fault by observing symptoms, forming a hypothesis, testing and confirming the repair. Working from power supply outwards and comparing with known-good values speeds diagnosis.

Scheduled cleaning, inspection, calibration and replacement carried out before failures occur. It reduces downtime and extends equipment life compared with repairing only after breakdown.

Comparing an instrument's readings against a known reference and adjusting it to reduce error. Records of calibration show whether measurements taken during testing can be trusted.

The activity of identifying an opportunity, organising resources and taking financial risk to start and run a business. It requires planning, costing, marketing and customer focus.

Calculating the full expense of producing or delivering a service, including materials, labour and overheads. Accurate costing sets a selling price that covers costs and yields a margin.

A commercial document listing goods or services supplied, their quantities, prices and the amount due. It supports payment claims, accounting records and any warranty or tax requirement.