CHSE Odisha Elective Electronics key terms

The rule stating that current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance, written V = IR, when temperature and other conditions stay constant.

A passive component made of two conducting plates separated by an insulator. It stores electric charge and energy in an electric field, and its opposition to changing voltage is called capacitance.

A passive component, usually a coil of wire, that stores energy in a magnetic field when current flows. It opposes sudden changes in current and has inductance measured in henries.

The total opposition a circuit presents to alternating current, combining resistance with reactance. It is a complex quantity measured in ohms and depends on signal frequency.

A thin zone near a pn junction where mobile charge carriers have diffused away, leaving fixed ionized atoms. This zone has few free carriers and creates an internal electric field and potential barrier.

The condition in which an external voltage reduces the potential barrier of a pn junction by connecting the p-side to the positive terminal and the n-side to the negative terminal, allowing substantial current.

A specially doped pn junction diode designed to operate safely in reverse breakdown. It maintains a nearly constant reverse voltage and is widely used for voltage reference and simple regulation.

A semiconductor diode that emits light when forward biased, because electrons and holes recombine and release energy as photons. Colour depends on the semiconductor material and its band gap.

A three-terminal semiconductor device with two pn junctions, having emitter, base, and collector regions. A small base current controls a larger collector current, enabling amplification and switching.

For a bipolar junction transistor in the active region, the ratio of collector current to base current, usually denoted beta or hFE. It indicates how strongly base current controls collector current.

A three-terminal device in which an electric field controls the conductivity of a channel between source and drain. Its control terminal, the gate, draws very little current, giving high input impedance.

The gate-source voltage at which a junction field-effect transistor's channel is fully depleted and drain current falls to nearly zero for a given small drain-source voltage.

The ratio of an amplifier's output voltage amplitude to its input voltage amplitude. It may be expressed as a plain number or in decibels, and it depends on frequency and load.

The process of feeding a portion of an amplifier's output back to its input with opposite phase, reducing gain but improving stability, bandwidth, distortion, and input or output impedance.

A bipolar transistor amplifier with the output taken from the emitter and no collector resistor. It provides voltage gain near unity, high input impedance, low output impedance, and is used as a buffer.

An amplifier stage in which each transistor conducts for about half of the input signal cycle. It is more efficient than class A but suffers crossover distortion unless biased slightly into class AB.

The condition for sustained oscillation in a feedback circuit: the loop gain must equal one and the total phase shift around the loop must be zero or a multiple of 360 degrees.

An oscillator that uses a quartz crystal as a resonant element. The crystal's piezoelectric property gives very stable, high-Q frequency control, making it suitable for clocks and radio equipment.

A wave-shaping circuit that removes portions of a waveform above or below a chosen voltage level, using diodes and resistors. It is used for protection and for converting sine waves into approximately square waves.

A comparator circuit with positive feedback that has two different switching thresholds. It converts slow or noisy waveforms into clean rectangular pulses and provides hysteresis, improving noise immunity.

The ratio of the alternating ripple voltage to the direct output voltage of a power supply. A small value indicates smooth DC output; filtering reduces it.

A circuit that holds a power supply's output voltage nearly constant despite changes in input voltage, load current, or temperature. It may be a simple Zener circuit or an integrated series regulator.

A measure of how much a power supply's output voltage changes when the load current changes from no load to full load, usually expressed as a percentage or voltage change.

A full-wave rectifier using four diodes arranged in a bridge. It converts both halves of the AC input into unidirectional current, without needing a centre-tapped transformer.

A basic digital circuit that performs a Boolean operation on one or more binary inputs to produce a single output. Common types include AND, OR, NOT, NAND, NOR, and XOR.

A table listing every possible combination of binary inputs to a logic circuit and the corresponding output for each combination, used to define and analyse digital behaviour.

Two Boolean algebra rules stating that the complement of an AND is the OR of the complements, and the complement of an OR is the AND of the complements. They help simplify logic circuits.

A bistable digital circuit with two stable output states, able to store one bit. Its output changes according to clock and input signals, making it the basis of registers and counters.

A modulation method in which the amplitude of a high-frequency carrier wave is varied in proportion to an information signal, while the carrier frequency and phase remain unchanged.

A modulation method in which the instantaneous frequency of a carrier wave is varied in proportion to an information signal, while the carrier amplitude stays essentially constant.

A number describing how strongly a carrier is modulated by the information signal. In amplitude modulation it is the sideband amplitude ratio; in frequency modulation it relates frequency deviation to modulating frequency.

The process of recovering the original information signal from a modulated carrier wave. It is performed by a detector or demodulator circuit in a radio receiver.

A test instrument that measures voltage, current, and resistance, and often additional quantities such as continuity or capacitance. It may be analogue with a moving pointer or digital with a display.

A measuring instrument that displays a signal's voltage waveform against time on a fluorescent screen. It allows measurement of amplitude, frequency, phase, and waveform shape.

A device that converts one form of energy into another, typically a physical quantity such as temperature, pressure, or light into an electrical signal for measurement or control.

A temperature-sensitive resistor whose resistance changes markedly with temperature. Negative-temperature-coefficient types decrease in resistance as they warm, making them useful for sensing and compensation.