Maharashtra SSC Electronics and Hardware Pre-Voc/NSQF key terms

The electrical pressure that pushes charge between two points in a circuit, measured in volts. A 9 V battery has 9 volts of potential difference across its terminals when not loaded.

The rate at which electric charge flows past a point in a circuit, measured in amperes. One ampere means one coulomb of charge passing each second.

The opposition a material offers to current flow, measured in ohms. Higher resistance means less current for the same applied voltage, and it converts electrical energy into heat.

The relationship stating that current equals voltage divided by resistance (I = V/R) in a linear conductor at constant temperature. It lets you calculate any one of the three quantities when the other two are known.

Two ways of connecting components. In series, current is the same through each part and voltages add; in parallel, voltage is the same across each branch and currents add.

A standard system of coloured bands printed on a resistor to show its value and tolerance. Each colour stands for a digit, and the last band shows how far the actual value may differ from the marked value.

A component that stores electrical charge in an electric field between two plates separated by a dielectric. It blocks steady direct current but passes changing signals, and is rated in farads and by working voltage.

A polarised capacitor with a metal oxide film as dielectric and a liquid or gel electrolyte, giving high capacitance in a small body. It must be connected with correct polarity or it can fail and vent.

A capacitor that must be connected with the positive terminal to the higher potential. Reversing it damages the dielectric and may cause overheating, leakage, or bursting, so the marked stripe shows the negative lead.

A coil of wire that stores energy in a magnetic field when current flows through it. It opposes changes in current and is used in filters, transformers, and chokes, with inductance measured in henries.

A device with two or more coils sharing a magnetic core that changes AC voltage levels by mutual induction. It works only on alternating current and is rated by its power in volt-amperes.

A two-terminal semiconductor device that conducts easily in one direction and blocks the other. It is used for rectification, protection, and clamping, with the banded end marking the cathode.

The two ways of applying voltage to a PN junction. Forward bias lets current flow easily once the barrier voltage is exceeded; reverse bias blocks current except for a tiny leakage current.

A circuit that converts alternating current into direct current using diodes. A half-wave rectifier uses one diode, while a full-wave bridge uses four and gives smoother output that needs less filtering.

A diode designed to work in reverse breakdown at a precise voltage. Connected with a series resistor, it holds a steady reference voltage and is used for voltage regulation and overvoltage protection.

A three-terminal semiconductor device that can amplify a signal or act as an electronic switch. In a bipolar transistor the terminals are base, collector, and emitter, and a small base current controls a larger collector current.

Setting the steady DC voltages and currents at a transistor's terminals so it works in the desired region, such as active, cut-off, or saturation. Correct bias keeps the output undistorted and the device within its ratings.

A complete circuit of many components fabricated on one small semiconductor chip and packaged with pins. ICs are identified by part number and pin-1 marking, and are handled with anti-static precautions.

An integrated circuit that holds its output voltage steady despite changes in input voltage or load current. Common fixed types are the 78xx positive series and 79xx negative series, which need input and output capacitors.

A test instrument that measures voltage, current, resistance, and often continuity and diode drop. Digital types show readings on an LCD; the correct function and range must be selected before probing.

An instrument that displays a signal as a graph of voltage against time on a screen. It shows waveform shape, amplitude, frequency, and noise, using controls for time base and vertical scale.

A check that shows whether a low-resistance path exists between two points, usually with a beep. It is done with the circuit unpowered and is used to trace wires and find open connections.

A meter that measures current without breaking the circuit by clamping around a single conductor and sensing its magnetic field. It suits high AC currents in mains wiring and motor circuits.

Joining metal parts with a filler alloy melted between them at a temperature below their melting points. In electronics, rosin-cored solder and a clean, tinned iron make a shiny, cone-shaped joint.

A chemical agent that removes oxide from metal surfaces and prevents new oxidation during soldering, helping the solder wet and bond. Rosin flux is standard for electronics; residues may need cleaning.

A soldered connection that looks dull, grainy, or ball-shaped because the joint did not reach proper temperature or the surfaces were dirty. It gives poor electrical contact and is a common cause of intermittent faults.

Removing solder from a joint to free a component, using a suction pump, desoldering braid, or hot-air station. Excess heat or force can lift pads and damage the board.

An insulating board with copper tracks and pads that connect components mechanically and electrically. Components are placed by their reference designators and soldered on the track side or through plated holes.

The two main component mounting styles. Through-hole parts have leads pushed through holes and soldered on the other side; surface-mount parts sit directly on pads and are reflow soldered.

A process where solder paste is printed on pads, components are placed, and the whole board is heated so the paste melts and forms joints. It suits surface-mount parts and needs a controlled temperature profile.

A sudden transfer of static charge between bodies at different potentials, which can destroy or weaken semiconductor devices. Prevention uses wrist straps, grounded mats, and conductive packaging.

A power supply that switches its input rapidly on and off to regulate output, giving high efficiency in a small size. It is found in computers and chargers and is repaired with attention to its high-voltage primary side.

An unintended low-resistance path that lets excessive current bypass the load. It causes blown fuses, overheating, or fire, and is located with continuity tests on an unpowered circuit.

A protective device with a metal element that melts and opens the circuit when current exceeds its rating. It must be replaced with the same rating and type, never with wire or a higher value.

Connecting exposed metal parts of equipment to earth so fault current flows safely away and protection operates. It reduces shock risk and is a mandatory safety requirement in mains-powered appliances.

Software that manages hardware resources and provides services for application programs, including memory, files, and devices. Examples are Windows, Linux, and Android, each with its own file system and interface.

A small software component that lets the operating system communicate with a specific piece of hardware such as a printer or graphics card. A missing or wrong driver makes the device fail or misbehave.

A Windows tool that lists installed hardware and shows its status, letting a technician update drivers, disable devices, and find fault codes. Warning icons there help diagnose non-working components.

A numeric label given to a device on a network so data can be sent to it. IPv4 uses four decimal groups; addresses may be set manually (static) or assigned by a DHCP server.

Two scales of network. A LAN covers a small area such as a lab or office and is usually owned by one organisation; a WAN links sites over long distances, often through a service provider.