The diode used in voltage-controlled oscillators is

 or diode

D) PIN diode
Answer: A) Gunn diode
Explanation:
Gunn diode operates on negative resistance principle and generates microwave oscillations.

---

93️⃣

Q: The diode which works on tunneling effect is
Options:
A) Zener diode
B) Tunnel diode
C) Varactor diode
D) Schottky diode
Answer: B) Tunnel diode
Explanation:
Due to heavy doping, electrons tunnel through barrier even at low voltages.

---

94️⃣

Q: The forward characteristic of tunnel diode shows
Options:
A) Negative resistance region
B) Positive resistance only
C) Linear region
D) Constant current
Answer: A) Negative resistance region
Explanation:
As voltage increases, current first rises then drops — giving negative resistance.

---

95️⃣

Q: The diode used in voltage-controlled oscillators is
Options:
A) Varactor diode
B) Tunnel diode
C) PIN diode
D) Schottky diode
Answer: A) Varactor diode
Explanation:
Its variable capacitance with reverse bias is used to tune oscillator frequency.

---

96️⃣

Q: The photodiode current is directly proportional to
Options:
A) Light intensity
B) Bias voltage
C) Temperature
D) Junction area
Answer: A) Light intensity
Explanation:
Higher light → more electron-hole pairs → higher photocurrent.

---

97️⃣

Q: The laser diode is similar to LED but
Options:
A) Emits incoherent light
B) Emits coherent light
C) Operates in reverse bias
D) Requires no bias
Answer: B) Emits coherent light
Explanation:
Laser diode emits coherent, monochromatic light by stimulated emission.

---

98️⃣

Q: A diode test using multimeter shows low resistance both ways. The diode is
Options:
A) Good
B) Open
C) Shorted
D) Reversed
Answer: C) Shorted
Explanation:
Low resistance in both directions indicates diode short circuit.

---

99️⃣

Q: A diode test shows infinite resistance both ways. The diode is
Options:
A) Shorted
B) Open
C) Good
D) Reversed
Answer: B) Open
Explanation:
No conduction in either direction means the diode junction is open.

---

100️⃣

Q: The most common application of a diode in electronics is
Options:
A) Amplifier
B) Rectifier
C) Oscillator
D) Modulator
Answer: B) Rectifier
Explanation:
Rectification (AC to DC conversion) is the most widespread application of diodes.