Maharashtra SSC Electronics Technology Pre-Voc/NSQF flashcards

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

Ohm's Law

Current through a conductor is directly proportional to voltage across it and inversely proportional to resistance, expressed as V = I × R.

Parallel Resistance Formula

Total resistance of parallel branches is found from 1/R = 1/R1 + 1/R2 + ...; the result is always smaller than the smallest branch resistance.

Kirchhoff's Current Law

At any junction, the total current entering equals the total current leaving, because charge cannot accumulate at a node in a steady circuit.

RMS Value

For a sinusoidal waveform, the RMS value equals peak value divided by the square root of two, about 0.707 times the peak.

Resistor Colour Code

First two bands give digits, third gives multiplier, fourth gives tolerance; gold means plus or minus five percent, silver ten percent.

Zener Diode

A diode designed to operate safely in reverse breakdown at a fixed Zener voltage, used as a shunt regulator or voltage reference in circuits.

Transistor Current Gain

Beta equals collector current divided by base current; emitter current equals collector current plus base current in a bipolar junction transistor.

LED Series Resistor

Resistance equals supply voltage minus LED forward voltage, divided by desired LED current, protecting the LED from excess current.

Bridge Rectifier

Four diodes arranged so both half cycles of AC are rectified; output ripple frequency is twice the supply frequency, 100 Hz on 50 Hz mains.

Voltmeter Connection

A voltmeter is connected in parallel with the component and should have very high resistance so it draws almost no current from the circuit.

CRO Time Measurement

Period equals horizontal divisions occupied by one cycle multiplied by the time-per-division setting; frequency is one divided by that period.

Voltage Divider

Output voltage equals input voltage times lower resistor divided by the sum of both resistors, valid when the output is not heavily loaded.

Cold Solder Joint

A dull, grainy or ball-shaped joint caused by insufficient heat or movement during cooling; it gives poor electrical contact and must be reworked.

Rosin Flux Function

Flux removes oxide film from pads and leads and improves wetting so molten solder flows and bonds properly to the metal surfaces.

ESD Wrist Strap

A conductive strap worn on the wrist and connected to earth through a resistor, safely draining static charge before it damages sensitive semiconductor devices.

PCB Pad

The copper land on a printed circuit board where a component lead or SMD terminal is soldered, connecting the part to the copper trace.

NAND Gate

A universal gate whose output is low only when all inputs are high; combinations of NAND gates can build every other logic function.

XOR Gate

A gate whose output is high when its two inputs differ and low when they are equal; it forms the sum output of a half adder.

De Morgan's Theorems

The complement of a product equals the sum of complements, and the complement of a sum equals the product of complements.

D Flip-Flop

A clocked one-bit memory element whose output takes the value present on the D input at the active clock edge and holds it.

7805 Regulator

A three-terminal fixed linear regulator giving a stable plus five volts output; input must be at least two to three volts higher.

Li-ion Charging

Constant current charging until 4.2 volts per cell, then constant voltage; protection circuits prevent overcharge, over-discharge and short-circuit damage.

Lead-Acid Cell Voltage

Each lead-acid cell delivers about two volts nominal, so a twelve-volt battery contains six cells connected in series inside one case.

SMPS Efficiency

Switch-mode supplies turn the switching device fully on and off rapidly, wasting little power as heat, so efficiency is typically seventy to ninety percent.

Microwave Magnetron

A vacuum tube that generates radio-frequency energy near 2.45 gigahertz, which heats food by agitating water molecules inside the oven cavity.

Refrigeration Cycle

Compressor raises refrigerant pressure and temperature, condenser releases heat, expansion valve drops pressure, evaporator absorbs heat from the cabinet.

IR Remote Testing

Point the remote at a digital camera and press a key; the camera shows the infrared LED blinking, confirming the remote transmits.

Arduino Uno ADC

Six analog inputs share a ten-bit converter; with a five-volt reference each step is about 4.9 millivolts, giving values zero to 1023.

LDR Sensor

A light-dependent resistor whose resistance falls as illumination increases; used with a fixed resistor as a voltage divider for light sensing.

Flyback Diode

A diode connected across a relay or motor coil to clamp the high voltage spike produced when the inductive load is switched off.

Lockout Tagout

Isolate the supply, fit a lock and warning tag so the circuit cannot be re-energised, then verify dead before starting work.

Break-Even Point

The sales quantity at which total revenue equals total cost, calculated as fixed cost divided by selling price minus variable cost per unit.