Basic Electronics Past Papers 


Subject: Basic Electronics

Time Allowed: 10 Minutes

Maximum Marks: 10

NOTE: Attempt this Paper on this Question Sheet only. Please encircle the correct option. Division of marks is given in front of each question. This Paper will be collected back after expiry of time limit mentioned above.


Part-I  Encircle the correct option, cutting and overwriting is not allowed. (10)

1. At room temperature, the current in an intrinsic semiconductor is due to
(a) holes (b) electrons
(c) ions (d) holes and electrons
2. Without a DC source, a clipper circuit resembles to a
(a) clamper (b) rectifier
(c) voltage doubler (d) none as above
3. If both the emitter-base and the collector-base junctions of a bipolar transistor are forward biased, the transistor is in the
(a) active region (b) saturated region
(c) cut-off region (d) inverse mode
4. The biasing technique that produces the most unstable Q-point is
(a) collector bias (b) emitter bias
(c) base bias (d) voltage-divider bias
5. In a certain voltage-divider biased npn transistor, Vg is 2.95 V. The de emitter voltage is approximately
(a) 2.25V (b) 2.95 V
(c) 3.65V (d) 0.7V
6. The disadvantage of base bias is that
(a) it is very complex (b) it produces low gain
(c) it is too beta (or hy.) dependent (d) it produces high leakage current
7. Ina voltage-divider biased npn transistor, if the upper voltage-divider resistor (the one connected to Vcc) opens,
(a) The transistor goes into cutoff (b) the transistor goes into saturation
(c) The transistor bums out (d) the supply voltage fs too high
8. The input resistance of a common-base (CB) amplifier is
{a) very high (b) very low
(c) the same as a CE (d) the same as a CC
9. A small-signal amplifier
(a) uses only a small portion of its load line (b) always has V,,, in the mV range
(c) goes into saturation once on each input cycle (d) is always a CE amplifier
10. The channel of a JFET is between the
(a) gate and drain (b) drain and source
(c) gate and source (a) input and output



Subject: Basic Electronics

Time Allowed: 2 Hours 45 Minutes

Maximum Marks: 50



Part-II Give short details of each of them, each answer carries equal marks. (20)

Q#1: What is peak reverse voltage (PRV)?

Q#2: Draw the circuit diagram of a voltage double circuit.

Q#3: Define the terms A, and he.

Q#4: If hg = 60 and IC = 1S5mA, what is the value of Ig and Ig?

Q#5: What do you mean by the term trans conductance?

Q#6: What is the cause of reverse saturation current?

Q#7: Why the common collector circuit called an emitter follower?

Q#8: What bias conditions must exist for a transistor to operate as an amplifier?

Q#9: Write down the role of input coupling capacitor in a transistor amplifier?

Q#10: What are two famous modes of operation for a MOSFET?


Part-III Give brief answers, each answer carries equal marks. (30)

Q#3: (a) Explain what the barrier potential is and how it is created in a pn junction?

(b) Discuss the circuit operation of a positive biased diode clipper and draw its output voltage waveform.

Q#4: (a) Draw the circuit for the common-emitter (CE) transistor amplifier, and derive expressions for its Current Gain, and the Voltage Gain.

(b) Trace the circuit diagram of a common-emitter (CE) self-biased circuit and discuss its circuit operation.

Q#5: (a) Explain the construction, symbol, working and characteristics of p-channel JFET.

(b) What is the construction difference between a JFET and MOSFET?

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