Electronic devices and circuits Past Papers


Subject: Electronic Devices and Circuits

Time Allowed: 15 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 right answer, cutting and overwriting are not allowed. (10)

1. if both the emitter-base and the collector-base junctions of a BJT are forward biased, the transistor is in the
(a) active region
(b) cut-off region
(c) saturated region
(d) inverse mode
2. When operated in cutoff and saturation, the transistor acts like
(a) a switch
(b) alinear amplifier
(c) an oscillator
(d) a variable resistor
3. The input resistance of a common-collector amplifier is
(a) very low
(b) very high
(c) the same as a CE
(d) none of these answers
4. The low-frequency response of an amplifier is determined by the
(a) coupling capacitors
(b) bias circuit
(c) transistor capacitances
(d) all of these answers
5. The bandwidth of an amplifier is defined by
(a) the midrange gain
(b) the critical frequencies
(c) the roll-off rate
(d) the inpuy capacitance
6. The efficiency of a power amplifier is the ratio of the power delivered to the load to the
(a) input signal power
(b) power dissipated in the last stage
(c) power from the dc power supply
(d) none of these answers
7. Crossover distortion is a problem for
(a) class A amplifiers
(b) class AB amplifiers
(c) class B amplifiers
(d) all of these amplifiers
8. The main feature of a crystal oscillator is
(a) economy
(b) beauty
(c) stability
(d) high frequency
9. In a Wien-bridge oscillator, if the resistances in the positive feedback circuit are decreased, the frequency
(a) decreases
(b) increases
(c) remains the same
(d) none of these answers
10. The triac is
(a) like a bidirectional SCR
(b) a four-terminal device
(c) not a thyristor
(d) both answers (a) and (b)