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Upwork Semiconductor Electronics Test Answer

1. A P-type material is _____.
Answers: • positively charged

2. According to the Barkhausen criterion for oscillators_______.

A – open loop gain
β – feed back factor
Answers: • Aβ > 1

3. If the reverse bias on the gate of an FET is increased , the width of the conducting channel will _____.
Answers: • decrease

4. An FET has the following parameters IDSS = 32mA , VGS ( off ) = -8V , VGS = -4.5V. What will be the drain current?
Answers: • 6.12 mA

5. For good stabilization of the operating point in a voltage divider bias, the current I, flowing through potential dividers R1 and R2, should be equal to or greater than _____.
(IB-base current)
Answers: • 10IB

6. If in a transistor IE = 10.5mA , IC = 10mA,the value of β will be _____.
Answers: • 200


7. A triac can pass a portion of _____.
Answers: • both positive and negative half-cycles through the load

8. An A.C supply of 230v is applied to a half wave rectifier circuit through a transformer of turn ratio 10:1. Its D.C voltage output will be _____.
Answers: • 10.36v

9. A vacuum tube conducts current _____.
Answers: • from the anode to the cathode

10. If a circuit of full-wave centre-tapped rectifier with capacitor filter employs a load RL = 100Ω, and C = 1050µF and the frequency is 50HZ , what would be the ripple factor?
Answers: • 22%

11. A varactor diode can function as a variable capacitor with a________ forward bias.
Answers: • heavy

12. Radio frequencies have their range above _____.
Answers: • 20KHZ

13. In the collector feedback biasing, β = 57 , RC = 1 kΩ , IB = 60µA and VCB = 4.5V. The value of the stability factor will be _____.
Answers: • 32.9

14. In the enhancement mode (MOSFET) , conductivity increases _____.
Answers: • with the increase in negative gate voltage

15. A three-stage amplifier has a first-stage voltage gain of 100, a second stage voltage gain of 200 and a third stage gain of 400. The total voltage gain in db will be _____.
Answers: • 140 dB

16. At parallel resonance, a tuned circuit offers an impedance of _____.
Answers: • R/LC

17. An SCR is a solid state equivalent of a _____.
Answers: • pentode

18. In the d.c. equivalent circuit of a transistor amplifier , the capacitors are regarded as _____.
Answers: • Unchanged

19. The maximum efficiency of a full wave rectifier is _____.
Answers: • 99%

20. If the collector supply voltage is 10v, the collector cut off voltage under D.C conditions will be _____.
Answers: • 10v

21. If the input to an integrating circuit is a square wave, the output will be _____.
Answers: • saw-tooth

22. If in a transistor , Ic = 9.5mA , Ie = 10mA , the value of α will be _____.
Answers: • 0.95

23. In an R-C phase shift oscillator, an R-C network is designed to introduce a phase shift of _____ .
Answers: • 300

24. If the input to a differentiating circuit is a square wave, the output will be _____.
Answers: • triangular

25. For faithful amplification, VBE must not fall below _____.
Answers: • 0.7v for si transistors

26. For an R-C phase shift oscillator , the frequency of oscillation will be given as _____.
Answers: • fo = 1/2П√RC

27. A reversed biased P-N junction has a resistance of the order of _____.
Answers: • MΩ

28. The impedance of a parallel tuned circuit at resonance is _____.
Answers: • low

29. A transistor amplifier has 4v,2mA as the operating point. For faithful amplification, the collector current due to signal alone should not exceed _____.
Answers: • 2mA

30. A D.C milliammeter connected to a half-wave rectifier supplying a maximum current of 10mA will read _____.
Answers: • 10 mA

31. An SCR combines the features of_____.
Answers: • a rectifier and a transistor

32. Hartley oscillator is _____.
Answers: • an LC oscillator

33. If in a transistor VCB= 4V , VBE = 0.7V, the VCE will be equal to _____.
Answers: • 4.7v

34. The input and output voltages of a CE transistor amplifier are _____.
Answers: • 180° out of phase

35. An FET has ________ temperature co-efficient of resistance.
Answers: • negative

36. An :FET is a _____.
Answers: • bipolar device

37. The complementary MOS(CMOS) uses _____.
Answers: • both n and p channel devices in the circuit

38. A 3-ohm load is coupled to a transistor amplifier through a step-down transformer. If the D.C resistance of the primary winding is 300Ω and the output resistance of the amplifier is 3KΩ, what should be the turn ratio for the transfer of maximum power?
Answers: • Np/Ns=30

39. The ideal value of the stability factor is _____.
Answers: • 1

40. If the A.C input to a half-wave rectifier has an R.M.S valve of 400/√2 v, the peak inverse voltage will be _____.

Answers: • 400√2 v

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