Assam ASSEB HS Skill Subject Electronics and Hardware flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's Law

The relationship V = I × R between voltage, current, and resistance. Given any two quantities, the third can be calculated directly, making it the basis for nearly all circuit analysis.

Kirchhoff's Voltage Law

The algebraic sum of all voltages around any closed loop equals zero. It reflects conservation of energy and is used to solve multi-element series circuits and mesh equations.

Kirchhoff's Current Law

The algebraic sum of currents entering and leaving a node equals zero. It reflects conservation of charge and is used for nodal analysis of parallel and branching circuits.

RC Time Constant

τ = R × C, the time for a capacitor to charge to about 63.2% of supply voltage. After five time constants the capacitor is considered fully charged.

RMS Voltage

The effective value of an AC waveform producing the same heating as an equal DC value. For a sine wave, V_rms equals V_peak divided by the square root of two.

Series Resonance

Occurs when inductive and capacitive reactances are equal, so they cancel. The resonant frequency is f₀ = 1/(2π√(LC)), and impedance is minimum at resonance.

Zener Diode Regulation

A Zener diode operated in reverse breakdown holds a nearly constant voltage across itself. A series resistor drops the excess supply voltage and limits current.

LED Series Resistor

The resistor limiting LED current is (V_supply − V_forward)/I_forward. Omitting it allows excessive current that destroys the LED almost immediately.

BJT Current Gain

In the active region, collector current equals beta times base current (I_C = β·I_B). Beta is typically 50 to 300 and varies with temperature and collector current.

MOSFET Gate Control

A MOSFET is controlled by gate-source voltage, not gate current, because the insulated gate draws virtually none. Enhancement types conduct only above threshold voltage.

Resistor Color Code

Bands encode value: black 0 through white 9, with the third band as multiplier. Gold and silver indicate tolerance of plus or minus five and ten percent.

Polarized Capacitor

An electrolytic capacitor has positive and negative terminals and must be connected with correct polarity. Reversed connection can cause overheating, leakage, and rupture.

De Morgan's Theorems

Two rules for inverting logic expressions: the complement of a product equals the sum of complements, and the complement of a sum equals the product of complements.

Universal Logic Gates

NAND and NOR gates are called universal because either alone can implement every other logic function, including AND, OR, and NOT, using appropriate combinations.

XOR Gate

The exclusive-OR gate outputs 1 only when its inputs differ, and 0 when they match. It forms the sum output of a half-adder and is used in parity checking.

D Flip-Flop

A clocked storage element whose output Q takes the value of input D at the active clock edge. It is the basic building block of registers and shift registers.

Karnaugh Map

A grid arranging truth-table outputs so adjacent cells differ by one variable. Grouping ones in powers of two yields a simplified Boolean expression for the circuit.

Multiplexer

A digital selector that routes one of several inputs to a single output, chosen by select lines. It is used for data routing and time-multiplexed signal sharing.

Microcontroller

A single chip containing a CPU, memory, timers, and input/output peripherals. It is designed for dedicated control tasks in embedded products rather than general computing.

ADC Resolution

The smallest voltage step an analog-to-digital converter can distinguish, equal to reference voltage divided by two to the power of bit count. More bits give finer resolution.

PWM Duty Cycle

The fraction of each period that a pulse stays high. It sets the average output voltage, enabling LED brightness and motor speed control without linear loss.

I²C Bus

A two-wire synchronous serial bus using data and clock lines. Multiple devices share the bus, each addressed individually, which suits sensors and small peripherals.

Watchdog Timer

A hardware counter that resets the microcontroller if firmware fails to clear it periodically. It recovers the system automatically from software hangs and lockups.

Voltmeter Connection

A voltmeter connects in parallel with the component being measured and must have very high resistance so it draws negligible current and does not disturb the circuit.

Oscilloscope Time Base

The horizontal scale in time per division. Multiplying the divisions occupied by one cycle by the time base setting gives the signal period and hence frequency.

True-RMS Meter

A meter that computes the actual heating-equivalent value of any waveform. Average-responding meters read incorrectly for non-sinusoidal signals such as square or distorted waves.

Wheatstone Bridge

Four resistive arms in a diamond, balanced when the ratio of arms is equal and no current flows through the detector. It measures unknown resistance accurately.

Cold Solder Joint

A dull, grainy, ball-shaped joint caused by insufficient heat or contaminated surfaces. It makes intermittent contact and should be reheated with flux and fresh solder.

Eutectic Solder

An alloy such as 63/37 tin-lead that melts at a single temperature, 183 °C, with no plastic phase. It solidifies quickly, reducing disturbed joints during hand soldering.

ESD Wrist Strap

A conductive band worn on the wrist and connected through a resistor to ground. It safely bleeds static charge from the technician before handling sensitive components.

LGA versus PGA

In LGA sockets the contact pins are on the motherboard socket; in PGA the pins are on the processor. Bent pins in either type prevent reliable contact.

CMOS Battery

A small cell on the motherboard that powers the real-time clock and stored BIOS settings when the system is unplugged. A dead cell causes clock and boot-configuration loss.