Karnataka KSEAB II PUC Electronics and Hardware (Vocational) key terms

A passive two-terminal component that limits current flow and creates a voltage drop, rated in ohms. Its value is marked by a colour code, and power rating must exceed the dissipation in the circuit.

A passive 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 its unit is the farad.

A coil of wire that stores energy in a magnetic field when current flows through it. It opposes changes in current, and its value in henries depends on turns, core material and geometry.

The relationship stating that current through a conductor is directly proportional to the voltage across it and inversely proportional to resistance, written V equals I times R, valid at constant temperature.

The standard banding system printed on resistors and some capacitors to indicate value and tolerance. Each colour maps to a digit, with a final band giving tolerance such as gold for five percent.

The permitted deviation of a component's actual value from its marked value, usually expressed as a percentage. A wider tolerance means the circuit design must work correctly over a larger spread of values.

A connection in which components form a single path so the same current flows through each. Total resistance is the sum of the individual resistances and the supply voltage divides between them.

A connection in which components share the same two nodes, so each has the full supply voltage across it while the total current splits between branches. Total resistance is always lower than the smallest branch.

Two resistors connected across a supply so the voltage across one is a fixed fraction of the supply, set by the resistance ratio. It is widely used to bias transistor bases and scale sensor outputs.

The insulating material between the plates of a capacitor, such as ceramic, polyester film or electrolytic paste. Its permittivity and thickness set the capacitance and the maximum working voltage.

A two-terminal semiconductor device with a p-n junction that conducts easily in one direction and blocks the other. It is used for rectification, protection and clamping, with a forward drop near 0.7 volts for silicon.

The narrow zone at a p-n junction where mobile carriers have diffused away, leaving fixed charged ions that create a barrier potential. It widens under reverse bias and narrows under forward bias.

A circuit that converts alternating current into pulsating direct current using one or more diodes. Half-wave uses one diode, while full-wave and bridge types use both halves of the input cycle.

A heavily doped diode designed to operate safely in reverse breakdown at a specified voltage. Biased with a series resistor, it holds a steady reference voltage for regulation and protection circuits.

A forward-biased semiconductor junction that emits light when electrons recombine with holes, with colour set by the material's band gap. It needs a series resistor to limit current.

A three-terminal device with emitter, base and collector formed by two junctions, in which a small base current controls a larger collector current. It is used for amplification and switching.

The ratio of collector current to base current in a bipolar transistor, written beta or hFE. It varies with temperature and operating current, so designs usually rely on feedback rather than exact gain.

Setting the steady direct voltages and currents at a device's terminals so it works in the intended region. For a transistor amplifier this means establishing a quiescent point midway on the load line.

The collector current and collector-emitter voltage that exist when no signal is applied, often called the operating or Q point. Correct placement prevents clipping of the amplified waveform.

The two extreme states of a switching transistor: cut-off when the base drive is removed so almost no collector current flows, and saturation when drive is excessive so the device acts almost as a closed switch.

A voltage-controlled transistor in which an electric field on the gate modulates conduction through a channel between source and drain. Its very high input resistance suits sensor and analogue front-end circuits.

A metal-oxide-semiconductor field effect transistor whose insulated gate draws almost no steady current. It is the standard device for power switching and for logic inside integrated circuits.

A circuit that increases the amplitude of a signal while drawing energy from a supply. Its performance is described by voltage gain, input and output impedance, bandwidth and distortion.

Returning a fraction of the output signal to the input in opposing phase. It reduces gain but improves stability, bandwidth, linearity and input impedance, and is fundamental to practical amplifier design.

The range of frequencies over which an amplifier's gain stays within a defined limit, usually three decibels below mid-band gain. It is bounded by the lower and upper cut-off frequencies.

A circuit that generates a continuous periodic output from a direct current supply without an external signal. It needs positive feedback with correct phase and loop gain of at least one.

Feeding part of the output back to the input in the same phase so the signal reinforces itself. Combined with a frequency-selective network it sustains oscillation in generators.

An oscillator whose frequency is fixed by a quartz crystal's mechanical resonance, giving very high stability. It is the usual clock source for microcontrollers and digital timing circuits.

A basic digital circuit that produces a defined output for every combination of binary inputs, following rules such as AND, OR, NOT, NAND and NOR. Gates are combined to build all digital systems.

A table listing every possible combination of inputs to a logic circuit alongside the required output for each. It is the definitive specification from which a logic expression or circuit is derived.

The mathematics of binary variables using operations AND, OR and NOT, with rules for simplifying expressions. Simplification reduces the number of gates needed to implement a function.

A grid arrangement of a truth table in which adjacent cells differ by one variable, allowing groups to be circled and simplified by inspection. It gives a minimal sum-of-products expression for small functions.

A bistable latch that stores one bit and changes state only on a clock edge or defined input. It forms the basis of registers, counters and memory in sequential logic.

A sequential circuit of flip-flops that counts clock pulses and outputs the count in binary or decimal. It is used for frequency division, timing and event counting.

A display of seven bar-shaped light emitting diodes arranged to form digits, driven either common-anode or common-cathode. Each segment needs a current-limiting resistor or a driver IC.

Two coupled windings on a shared magnetic core that transfer alternating energy by mutual induction, changing voltage in proportion to the turns ratio. It also provides isolation between mains and the low-voltage side.

A large capacitor placed after a rectifier to charge on voltage peaks and discharge into the load, smoothing the pulsating output. Larger values and lighter loads reduce the remaining ripple.

The small alternating variation remaining on a direct current supply after smoothing. It is quoted as a peak-to-peak or rms voltage and should be low for sensitive analogue and digital loads.

A circuit that holds its output voltage constant despite changes in input voltage or load current. Types include series pass regulators, three-terminal integrated regulators and switching regulators.

A general-purpose instrument that measures voltage, current and resistance, and often continuity and diode drop. Correct range and terminal selection are essential to avoid damage or unsafe readings.

An instrument that plots signal voltage against time on a screen, letting the user measure amplitude, period, frequency and waveform shape. Modern versions are digital and can store and trigger on events.

Joining metal surfaces with a filler alloy melted at a temperature below the workpieces' melting points. In electronics, rosin flux and eutectic tin-lead or lead-free solder form a reliable electrical and mechanical bond.

A chemical agent applied during soldering that removes oxide films and helps molten solder wet the surfaces. Rosin-based flux is standard for electronics because residues are non-corrosive.

A soldered connection where the solder did not properly wet the pad or lead, giving a dull, lumpy or cracked appearance and an unreliable, often intermittent, electrical contact. It is usually reworked.

Removing solder from a joint using a suction pump, desoldering braid or hot-air tool so a component can be extracted without damaging the board or pads. Extra flux and fresh solder often help.

An insulating board with copper tracks and pads that both support components and connect them electrically. Design rules cover track width, clearance, pad size and layer stack-up.

A construction method in which components are soldered directly onto pads on the board surface rather than through holes. It allows smaller boards and automated assembly but demands careful placement and reflow control.

A process where solder paste is printed on pads, components are placed, and the board is heated through a controlled profile so the paste melts and forms joints. It is standard for surface mount assembly.

A single integrated circuit containing a processor core, memory, timers and input-output peripherals, programmed to control a device. It is the heart of most embedded products.

General purpose input-output pins on a microcontroller that software can configure as digital inputs or outputs, often with internal pull-up resistors and alternate functions such as serial or PWM.

A peripheral that samples a continuous voltage and converts it to a binary number, with resolution in bits and a reference voltage setting the scale. It lets a microcontroller read sensors.

Rapidly switching a digital output on and off with a variable duty cycle so the load sees an adjustable average voltage or power. It dims lamps, controls motor speed and synthesises tones.

A device that converts a physical quantity such as temperature, light, pressure or position into an electrical signal. Its output may be analogue, digital or a variable resistance.

A device that converts one form of energy into another, such as a thermistor changing resistance with temperature or a loudspeaker changing current into sound. Sensors and actuators are transducers.

A dedicated computer built into a product to perform a specific control task, typically using a microcontroller with firmware and interfaces to sensors and actuators, often with real-time constraints.