RBSE Sec Voc Electronics and Hardware key terms

The electrical pressure that pushes charge between two points in a circuit, measured in volts. It is the energy transferred per unit charge and drives current through a resistance.

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

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

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

The rate at which electrical energy is used or delivered, measured in watts. It equals voltage multiplied by current, and also equals current squared times resistance.

Current that flows in one constant direction with steady polarity. Batteries and typical power-supply outputs deliver DC, which most electronic circuits require to operate.

Current whose direction and magnitude reverse periodically, usually as a sine wave. Mains supply is AC, described by its frequency and root-mean-square value.

The root-mean-square value of an AC waveform, equal to the steady DC value that would produce the same heating effect. For a sine wave it is peak value divided by about 1.414.

A passive component that limits current and sets voltage levels in a circuit. Its value in ohms is shown by a colour code, and its power rating must not be exceeded.

A standard banding scheme on resistors where each colour represents a digit, multiplier, or tolerance. Reading the bands gives the resistance value and acceptable deviation.

A passive component that stores energy in an electric field between two plates, blocking DC while passing AC. Capacitance is measured in farads and printed with a voltage rating.

A passive component, usually a coil, that stores energy in a magnetic field and opposes changes in current. Its value is measured in henries and it passes DC more readily than AC.

The permitted variation of a component's actual value from its marked value, usually given as a percentage. A tighter tolerance means the part is more precise and generally more costly.

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

The small voltage lost across a conducting diode, roughly 0.7 V for silicon and 0.3 V for germanium types. It must be allowed for when calculating circuit voltages.

A circuit that converts alternating current into pulsating direct current using diodes. Half-wave types use one diode, while full-wave and bridge types use two or four.

A three-terminal semiconductor device with base, collector, and emitter, used for amplification or switching. A small base current controls a much larger collector current.

Setting the steady DC voltages and currents at a transistor's terminals so it operates in the intended region. Correct bias keeps a signal amplifier linear and prevents distortion.

A voltage-controlled semiconductor device in which an electric field at the gate regulates current between source and drain. It draws almost no gate current and is common in switching circuits.

A digital circuit block that produces a defined output for each combination of binary inputs. Common types include AND, OR, NOT, NAND, NOR, and exclusive-OR.

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

A set of rules for manipulating binary variables using operations such as AND, OR, and NOT. It is used to simplify logic expressions before building circuits.

A bistable digital storage element that holds one bit until changed by a clock or input signal. It forms the basis of registers and counters in sequential logic.

A digital selector that routes one of several inputs to a single output according to control signals. It reduces the number of lines needed to carry multiple signals.

A general-purpose instrument that measures voltage, current, and resistance, available in analog or digital form. Correct range and function selection is essential before probing a circuit.

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

A check that confirms an unbroken electrical path, often signalled by a beep. It is performed with power removed and is used to trace wiring and find open connections.

The maximum instantaneous magnitude reached by a varying waveform during one cycle. For a sine wave it is the RMS value multiplied by about 1.414.

A low-melting-point metal alloy, commonly tin with lead or a lead-free mix, used to join components electrically and mechanically. Its melting range and flux content suit hand and reflow work.

A chemical agent in solder or applied separately that removes oxide from metal surfaces during heating. It helps molten solder wet the joint and form a sound connection.

A poor solder connection caused by insufficient heat or a disturbed joint during cooling. It looks dull and grainy, has high resistance, and causes intermittent faults.

An insulating board with copper tracks that connect mounted components, replacing bulky point-to-point wiring. It provides repeatable layout, mechanical support, and solder pads.

A small plated hole in a printed circuit board that connects copper tracks on different layers. It carries signals or power between layers without a component lead.

A component mounting style in which leads pass through holes in the board and are soldered on the far side. It gives strong mechanical joints and suits connectors and larger parts.

Volatile working memory that holds programs and data currently in use, losing content when power is removed. Insufficient or faulty RAM causes slow performance or boot failures.

Non-volatile memory that retains stored data without power and normally cannot be rewritten during use. It holds firmware such as the boot program that starts a computer.

Firmware that tests hardware at power-up and starts the operating system from a boot device. Its settings control low-level options such as boot order and device configuration.

Any external device attached to a computer to add input, output, or storage functions. Keyboards, printers, and drives connect through standard ports and need matching drivers.

Software that lets the operating system communicate with a specific piece of hardware. A missing or mismatched driver commonly causes a device to fail or behave erratically.

A standard serial interface for connecting peripherals and supplying power over one cable. It supports hot swapping and several speed generations with compatible connectors.

A supply that converts input power by rapidly switching it on and off, then filtering the result. It is efficient and compact but generates high-frequency electrical noise.

A capacitor placed across a rectifier output to smooth the pulsating DC into a steadier voltage. Larger capacitance reduces ripple but draws a higher surge current at switch-on.

A sacrificial protective device containing a wire that melts when current exceeds its rating, breaking the circuit. It must be replaced with the same rating, never bypassed.

Connecting exposed metalwork to the earth so fault current flows safely away and protective devices trip. It limits shock risk and keeps chassis potential near zero.

A safety procedure that isolates energy sources and attaches warning tags before maintenance begins. It prevents accidental start-up or release of stored energy while work is in progress.

Wearable gear such as safety glasses, gloves, and footwear that reduces injury risk. It is the last line of defence and never replaces safe procedures or guards.

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

The process of identifying an opportunity, organising resources, and taking financial risk to start and run a business. It combines initiative, planning, and willingness to accept uncertainty.

The sales level at which total revenue equals total cost, so neither profit nor loss is made. Knowing it helps a small workshop set prices and judge minimum workload.

The money available for day-to-day operations, calculated as current assets minus current liabilities. Shortage of it is a common reason small hardware businesses fail.

A written summary of a candidate's education, skills, and experience used when applying for work. It should be truthful, concise, and tailored to the job advertised.

Researching an employer and rehearsing answers about skills and experience before a job interview. It includes preparing examples of past work and questions to ask.

A commercial document listing goods or services supplied, their quantities, prices, and payment terms. It serves as a demand for payment and a record for both parties.

A buyer's formal written request authorising a supplier to provide stated goods at agreed prices. It fixes quantities and terms before delivery and is matched against the invoice.

An indirect tax added to the supply of goods and services, collected by the seller and remitted to government. Registered businesses must show it correctly on invoices and returns.