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Solution to Previous Year Exam Questions pyq for Basic Electronics - BE of 2018 - BDCOE by Upesh Patel

  • Basic Electronics - BE
  • 2018
  • PYQ Solution
  • Rashtra Santh Tukduji Maharaj Nagpur University - RTMNU
  • Electrical and Electronics Engineering
  • B.Tech
  • 137 Offline Downloads
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Code: DE06 Subject: BASIC ELECTRONICS PART – I, VOL - I TYPICAL QUESTIONS & ANSWERS OBJECTIVE TYPES QUESTIONS Each Question carries 2 marks Choose correct or the best alternative in the following: Q.1 A resistor with colour bands Red, Violet, Green and Black will have a value (A) 27 K ± 10% K (C) 270 K ± 5% K (B) 2.7 M ± 20% K (D) 2.7 K ± 2% K Ans: B Q.2 In an n-type semiconductor, as temperature T increases, the Fermi level EF (A) moves towards conduction band (B) moves towards middle of forbidden energy gap (C) does not vary (D) may or may not shift depending upon the concentration of donor atoms Ans: A Q.3 In a BJT with β = 100, α equals (A) 99 (C) 1.0 (B) 0.99 (D) 1.01 Ans: C Q.4 In integrated circuits, npn construction is preferred to pnp construction because (A) npn construction is cheaper (B) to reduce diffusion constant, n-type collector is preferred (C) npn construction permits higher packing of elements (D) p-type base is preferred Ans: B Q.5 Pinch-off voltage VP for an FET is the drain voltage at which (A) significant drain current starts flowing (B) drain current becomes zero (C) all free charges get removed from the channel (D) avalanche break down takes place Ans: C 1

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Code: DE06 Q.6 Subject: BASIC ELECTRONICS In SCR, the turn ON time (A) is independent of Vg (B) decreases with increase of Vg (C) varies as Vg 2 (D) varies as Vg Ans: A Q.7 Avalanche breakdown results basically due to (A) impact ionisation (B) strong electric field across the junction (C) emission of electrons (D) rise in temperature Ans: A Q8 Dynamic plate resistance of pentode is of the order of (B) 10 K Ω (A) 1 K Ω (C) 100 K Ω (D) 1M Ω Ans: D Q.9 At room temperature, the current in an intrinsic semiconductor is due to (A) holes (C) ions (B) electronics (D) holes and electronics Ans: D Q.10 The varactor diode is usually (A) Forward biased (C) Unbiased (B) reverse biased (D) holes and electronics Ans: B Q.11 The diode in which impurities are heavily doped is (A) Varactor diode (C) Tunnel diode (B) PIN diode (D) Zener diode Ans: C Q.12 A transistor in common emitter mode has (A) a high input resistance and low output resistance (B) a medium input resistance and high output resistance (C) a very low input resistance and a low output resistance (D) a high input resistance and a high output resistance Ans: B 2

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Code: DE06 Q.13 Subject: BASIC ELECTRONICS In an SCR the holding current is (A) more than latching current (C) equal to latching current (B) less than latching current (D) very small Ans: B Q.14 The negative potential at the control grid in a vacuum triode that causes plate current Zero is called (A) cut off bias (C) reverse blocking voltage (B) cut in voltage (D) forward blocking voltage Ans: A Q.15 A constant current source supplies a current of 300 mA to a load of 1 Kohm. When the Load is changed to 100 ohm, the load current will be (A) 3 Amp (C) 30 mAmp (B) 300 mAmp (D) 600 mAmp Ans: B Q.16 An Op-amp as a voltage follower has a voltage gain of (A) Infinity (C) Unity (B) Zero (D) less than unity Ans: C Q.17 A resistor used in colour TV has the following colour bands: yellow, violet, orange and silver. Its nominal value is (A) 4.7 K Ω ± 10 % (C) 47 K Ω ± 10 % (B) 4.7 K Ω ± 5 % (D) 470 K Ω ± 5 % Ans: C Q.18 Ratings on a capacitor are given 25 µ F, 12 V. Also a plus sign is written near one of its terminals. The capacitor is (A) mica capacitor (C) electrolytic capacitor (B) ceramic capacitor (D) paper capacitor Ans: C Q.19 An ideal voltage source of 12 V provides a current of 150 mA to a load connected across it. If the load impedance is halved, the new load current will be (A) 0.3 A (C) 0.6 A (B) 0.15 A (D) 1.2 A Ans: A 3

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Code: DE06 Q.20 Subject: BASIC ELECTRONICS An intrinsic semiconductor at the absolute zero temperature (A) behaves like a metallic conductor (B) behaves like an insulator (C) has a large number of holes (D) has a large number of electrons Ans: B Q.21 Which of the following diodes is operated in reverse bias mode ? (A) P-N junction (C) Tunnel (B) Zener (D) Schottky Ans: B Q.22 Compared to bipolar transistor, a JFET has (A) lower input impedance (B) higher voltage gain (C) higher input impedance and high voltage gain (D) higher input impedance and low voltage gain Ans: D Q.23 The minimum gate current which can turn on SCR is called (A) trigger current (C) junction (B) holding current (D) break over current Ans: A Q.24 A virtual ground (A) is a ground for voltage (B) is a ground for both voltage and current (C) is ground for current (D) is a ground for voltage but not for current Ans: D Q.25 Which of the following doping will produce a p-type semiconductor (A) Germanium with phosphorus (C) Germanium with Antimony (B) Silicon with Germanium (D) Silicon with Indium Ans: D Q.26 The majority charge carriers in the emitter of an NPN transistor are (A) pentavalent atoms (C) electrons (B) trivalent atoms (D) holes Ans: C 4

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