RBSE Sec Voc Electronics and Hardware flashcards
RBSE Sec Voc Electronics and Hardware · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Ohm's law
- For a resistive circuit, voltage equals current multiplied by resistance (V = I × R). Knowing any two quantities lets you calculate the third.
- Series circuit current
- In a series circuit the same current flows through every component, while the supply voltage divides across them in proportion to their resistances.
- Parallel circuit voltage
- In a parallel circuit the voltage across each branch is identical, branch currents add, and total resistance is smaller than any single branch resistance.
- RMS value of sine
- The RMS value of a sinusoidal waveform equals the peak value divided by the square root of two, roughly 0.707 times peak.
- Resistor colour code
- Colour bands give digits and multiplier: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9.
- Capacitor code 104
- A ceramic capacitor marked 104 has a value of 10 × 10⁴ picofarads, which equals 100 nanofarads or 0.1 microfarad.
- Electrolytic capacitor polarity
- Electrolytic capacitors are polarized and must be connected with correct polarity. Reversing the voltage damages the dielectric and can cause the case to vent.
- Transformer turns ratio
- The ratio of primary to secondary voltage equals the ratio of primary to secondary turns, so a step-down transformer has fewer secondary turns.
- Silicon diode forward drop
- A forward-biased silicon diode drops about 0.7 volts across it, while a germanium diode drops roughly 0.3 volts.
- Zener diode regulation
- A Zener diode operated in reverse breakdown holds a nearly constant voltage, so it is used with a series resistor to regulate a supply.
- Transistor saturation region
- In saturation the transistor is fully on, collector current is limited mainly by the external load, and Vce falls to about 0.2 volts.
- LED series resistor
- The resistor value is supply voltage minus LED forward voltage, divided by the desired LED current in amperes.
- Universal logic gates
- NAND and NOR are called universal gates because either one alone can be wired to produce NOT, AND, OR, and every other logic function.
- XOR gate behaviour
- An exclusive-OR gate outputs 1 only when its inputs differ. Combined with an AND gate it forms a half adder.
- De Morgan's theorems
- De Morgan's theorems state that the complement of a product equals the sum of the complements, and the complement of a sum equals the product of the complements.
- D flip-flop
- A D flip-flop captures the value present on its data input at the active clock edge and holds that value at the output until the next edge.
- Ammeter connection
- An ammeter is connected in series with the circuit and has very low internal resistance so it does not disturb the current being measured.
- Oscilloscope frequency reading
- Period equals horizontal divisions times time-per-division; frequency is one divided by that period. Volts/division gives amplitude.
- Clamp meter use
- A clamp meter measures current by surrounding a single conductor with its jaw; enclosing both supply and return conductors cancels the field and reads zero.
- Insulation resistance test
- A megger applies a high test voltage to an isolated, discharged circuit to verify insulation resistance, usually measured in megohms.
- Good solder joint
- A sound solder joint is shiny, smooth, and concave, showing the solder wetted both pad and lead rather than sitting as a ball.
- Cold solder joint
- A cold joint looks dull and grainy because the joint did not reach soldering temperature; it causes intermittent or high-resistance connections.
- ESD wrist strap
- An anti-static wrist strap contains a high-value resistor, typically one megohm, that bleeds static charge slowly while limiting current if the wearer touches live voltage.
- Solder bridge defect
- A solder bridge is an unintended blob of solder connecting two adjacent pads or tracks, causing a short circuit on the board.
- POST beep codes
- Power-on self-test beep patterns report faults before the display initialises; repeated beeps usually indicate memory or graphics failure.
- ATX 12 volt wire
- In a standard ATX power connector the yellow wires carry +12 volts, red carry +5 volts, orange carry +3.3 volts, and black are ground.
- Thermal paste purpose
- Thermal paste fills microscopic air gaps between the processor and heatsink, improving heat transfer. A thin even layer works best.
- CMOS battery role
- A small coin cell keeps the real-time clock running and preserves BIOS settings when the computer is unplugged from mains power.
- SMPS efficiency
- A switched-mode supply switches at high frequency, so the transformer and filter are small and efficiency is high, but output capacitors stay charged after switch-off.
- Bridge rectifier ripple
- A full-wave bridge rectifier produces two output pulses per input cycle, so the ripple frequency is twice the AC supply frequency.
- 7805 regulator output
- The 7805 is a fixed linear regulator giving a +5 volt output; the 79xx series provides fixed negative outputs instead.
- Electric shock current levels
- About 1 milliampere is perceptible, 10 to 30 milliamperes can cause muscle lock, and 50 milliamperes and above can be fatal.