Electronic Components and Devices Flashcards
7 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electronic Components and Devices flashcards as text
What is the main advantage of a Darlington pair transistor configuration?
Answer: Very high current gain (β²)
A Darlington pair multiplies the current gains of two transistors, yielding an overall β approximately equal to β1 × β2.
An inductor with 50 mH inductance carries a current of 2 A. What is the energy stored?
Answer: 0.1 J
Energy stored in an inductor = ½LI² = ½ × 0.05 × 4 = 0.1 J.
Which semiconductor device exhibits negative resistance and is used in microwave oscillators?
Answer: Tunnel diode
The tunnel diode exhibits negative resistance due to quantum tunneling, making it useful in high-frequency oscillator circuits.
What is the function of a varactor (varicap) diode?
Answer: Act as a voltage-variable capacitor
A varactor diode's junction capacitance varies with reverse bias voltage, making it useful as a voltage-controlled tuning element.
In a common-collector BJT amplifier (emitter follower), which characteristic is most notable?
Answer: Very high input impedance and low output impedance
The emitter follower has unity voltage gain, very high input impedance, and very low output impedance, making it ideal for impedance matching.
Which type of resistor has a resistance that decreases significantly as temperature increases?
Answer: NTC thermistor
An NTC (Negative Temperature Coefficient) thermistor decreases in resistance as temperature rises.
A TRIAC differs from an SCR in that a TRIAC can:
Answer: Conduct current in both directions
A TRIAC is essentially two SCRs in parallel in opposite directions, allowing it to control AC by conducting in both directions.