MCQOPTIONS
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MCQOPTIONS
This section includes 1136 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
In oscillator circuits the energy feedback to its input terminal from output is |
| A. | always in phase with the input signal |
| B. | 90° out of phase with the input signal |
| C. | 180° out of phase with the input signal |
| D. | 270° out of phase with the input signal |
| Answer» D. 270¬∞ out of phase with the input signal | |
| 202. |
CMRR of a difference amplifier is equal to |
| A. | (Av')/(Acom) |
| B. | Av/Acom |
| C. | Acom/Av' |
| D. | (Av)/(Acom)2 |
| Answer» B. Av/Acom | |
| 203. |
In switching devices, gold doping is used to |
| A. | improve bonding |
| B. | reduce storage time |
| C. | increase the mobility of the carrier |
| D. | protect the terminals against cooperation |
| Answer» C. increase the mobility of the carrier | |
| 204. |
The main advantage of a crystal oscillator |
| A. | can oscillate any frequency |
| B. | gives a high output voltage |
| C. | frequency of oscillation is almost constant |
| D. | can operates at a low dc voltage |
| Answer» D. can operates at a low dc voltage | |
| 205. |
In a transistor push pull amplifier |
| A. | there is no dc present in the output |
| B. | there are no even harmonics in the output |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 206. |
Which amplifier has a voltage gain of less than 1? |
| A. | Common emitter |
| B. | Common collector |
| C. | Common base |
| D. | Both CB and CC |
| Answer» C. Common base | |
| 207. |
The equivalent circuit shown in figure is for |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | None of the above |
| Answer» D. None of the above | |
| 208. |
A silicon PN junction diode under reverse bias has depletion region of width 10 μm. The relative permittivity of silicon, εr = 11.7 and the permittivity of free space ε0 = 8.85 x 10-12 F/m. The depletion capacitance of the diode per square meter is |
| A. | 1 μF |
| B. | 20 μF |
| Answer» C. | |
| 209. |
In a CE amplifier the Q point is very close to cutoff point on the load line. This results in |
| A. | saturation clipping |
| B. | cut off clipping |
| C. | both saturation and cut off clipping |
| D. | either saturation clipping or cut off clipping |
| Answer» C. both saturation and cut off clipping | |
| 210. |
A pulse transformer uses |
| A. | ferrite core |
| B. | air core |
| C. | iron core |
| D. | copper core |
| Answer» B. air core | |
| 211. |
In order to protect a MOSFET against damage from any stray voltage at the gate |
| A. | grounding rings are provided |
| B. | terminals are shorted |
| C. | source terminal is earthed during transit |
| D. | none of these |
| Answer» D. none of these | |
| 212. |
The phase angle of a lag circuit is |
| A. | between 0 and -90° |
| B. | between 0 and +90° |
| C. | 90° |
| D. | more than 90° |
| Answer» C. 90¬∞ | |
| 213. |
The IF amplifier in a superheterodyne receiver is |
| A. | single-stage single-timed amplifier |
| B. | two stage of single tuned amplifier |
| C. | double tuned amplifier |
| D. | class-C amplifier |
| Answer» C. double tuned amplifier | |
| 214. |
Which op-amp circuit uses a diode as one of the circuit components? |
| A. | Integrating amplifier |
| B. | Differentiating amplifier |
| C. | Logarithmic amplifier |
| D. | Summing amplifier |
| Answer» D. Summing amplifier | |
| 215. |
In the circuit of figure, the value of re is (neglecting vbe) |
| A. | 100 Ω |
| B. | 75 Ω |
| C. | 50 Ω |
| D. | 25 Ω |
| Answer» E. | |
| 216. |
To have a centred Q point in CE amplifier |
| A. | ac resistance of collector circuit |
| B. | ac resistance of emitter circuit |
| C. | ac resistance of collector and emitter circuit |
| D. | ac resistance of collector and emitter circuit |
| Answer» D. ac resistance of collector and emitter circuit | |
| 217. |
A major advantage of TWT over a Klystron lies in its |
| A. | higher bandwidth |
| B. | higher gain |
| C. | higher frequency |
| D. | higher output |
| Answer» C. higher frequency | |
| 218. |
In the CE equivalent circuit of figure, the voltage gain is |
| A. | 5 |
| B. | 1000 |
| Answer» B. 1000 | |
| 219. |
Which of the following best represents the bandwidth of an actual op-amp? |
| A. | 100 Hz to 1 MHz |
| B. | 0 Hz to 100 kHz |
| C. | 0 Hz to 10 MHz |
| D. | 0 Hz to infinity |
| Answer» C. 0 Hz to 10 MHz | |
| 220. |
The op-amp circuit shown in the figure is a filter. The type of filter and its cut off type of filter and its cut off frequency are respectively. |
| A. | high Pass, 1000 rad/sec |
| B. | low Pass, 100 rad/sec |
| C. | high Pass, 10000 rad/sec |
| D. | low pass, 10000 rad/sec |
| Answer» B. low Pass, 100 rad/sec | |
| 221. |
If the plate supply voltage for a plate modulated class C amplifier is E volts, the maximum plate-cathode voltage could be almost as high as |
| A. | E |
| B. | E/2 |
| C. | 2E |
| D. | 4E |
| Answer» E. | |
| 222. |
In the circuit of figure v1 = 8 V and v2 = 0. Which diode will conduct (Assume ideal diodes)? |
| A. | D1 only |
| B. | D2 only |
| C. | Both D1 and D2 |
| D. | Neither D1 nor D2 |
| Answer» B. D2 only | |
| 223. |
The input differential stage of op-amp. 741 is baised at about 10 μA current such a low current of the input stage gives high CMRRhigh differential gainlow differentialhigh input impedance Which of these are correct? |
| A. | 1 and 2 |
| B. | 1, 2 and 4 |
| C. | 3 and 4 |
| D. | 1, 2, 3 and 4 |
| Answer» C. 3 and 4 | |
| 224. |
In figure, VC is approximately equal to |
| A. | 2 V |
| B. | 4.6 V |
| C. | 8 V |
| D. | 7.6 V |
| Answer» D. 7.6 V | |
| 225. |
Equal amplitude ac signals are given as inputs to both inverting and given as inputs to both inverting and non-inverting terminals of an op-amp. The output will be zero when the phase difference between inputs is |
| A. | 0° |
| B. | 90° |
| C. | 180° |
| D. | 270° |
| Answer» B. 90¬∞ | |
| 226. |
An ideal voltage amplifier should have |
| A. | low input impedance and high output impedance |
| B. | high input impedance and low output impedance |
| C. | high input impedance and high output impedance |
| D. | low input impedance and low output impedance |
| Answer» C. high input impedance and high output impedance | |
| 227. |
In a normally biased N-P-N transistor the main current crossing the collector junction is |
| A. | a drift current |
| B. | a hole current |
| C. | a diffusion current |
| D. | same as the base current |
| Answer» B. a hole current | |
| 228. |
A transistor amplifier is operating in class A mode. If a transformer is connected for impedance matching, the efficiency will |
| A. | increase |
| B. | decrease |
| C. | not be affected |
| D. | increase or decrease |
| Answer» B. decrease | |
| 229. |
As the ratio Rf/RL increases the efficiency of a rectifier increases. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 230. |
If ac resistance of diode is re, then In CE, BJT amplifier the input impedance is |
| A. | re |
| B. | β re |
| C. | |
| Answer» C. | |
| 231. |
In figure the source resistance of current source IEE is infinite, then common mode gain is |
| A. | infinite |
| B. | zero |
| C. | indeterminate |
| Answer» B. zero | |
| 232. |
In a diode rectifier with a capacitance input filter, a surge current is likely to flow when the circuit is switched on. The cause of this surge current is |
| A. | the non linear behaviour of diodes |
| B. | the capacitor acts as a short circuit at the instant of switching, |
| C. | the inductance of leads |
| D. | both (a) and (b) |
| Answer» C. the inductance of leads | |
| 233. |
The common-drain amplifier, better known as the source follower, has a voltage gain __________ and the output signal is __________ with the input signal. |
| A. | approaching unity, in phase |
| B. | approaching unity, out of phase |
| C. | is very high, in phase |
| D. | is very high, in reverse phase |
| Answer» B. approaching unity, out of phase | |
| 234. |
The current through R1 is(If β = 99, VBE = 0.74 V) |
| A. | 0.1 mA |
| B. | 0.35 mA |
| C. | 0.2 mA |
| D. | none |
| Answer» B. 0.35 mA | |
| 235. |
In figure, ID = 4 mA. Then VS = |
| A. | 20 V |
| B. | 16 V |
| C. | 6 V |
| D. | 0.6 V |
| Answer» D. 0.6 V | |
| 236. |
In the circuit of figure, v1 = v2 = 10 V. Then |
| A. | I1 = I2 |
| B. | I1 > I2 |
| C. | I2 > I1 |
| D. | I1 = 0 |
| Answer» D. I1 = 0 | |
| 237. |
A transistor with a = 0.98 then β will be |
| A. | 49 |
| B. | 50 |
| C. | 47 |
| D. | 48 |
| Answer» B. 50 | |
| 238. |
Assertion (A): The maximum efficiency of a class B push pull amplifier is 78.5%Reason (R): A current mirror uses a compensating diode in parallel with the emitter diode |
| A. | A is correct R is wrong |
| B. | A is wrong R is correct |
| Answer» C. | |
| 239. |
Figure uses 10 V zener diode. The minimum and maximum current through series resistance are |
| A. | 10 mA and 30 mA |
| B. | 20 mA and 40 mA |
| C. | 0 and 30 mA |
| D. | 0 and 40 mA |
| Answer» B. 20 mA and 40 mA | |
| 240. |
A low noise device is most important |
| A. | at front end of equipment |
| B. | in the last stage of equipment |
| C. | in the middle stages of equipment |
| D. | both (b) and (c) |
| Answer» B. in the last stage of equipment | |
| 241. |
An integrating amplifier has resistance in feedback path. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 242. |
Zero bias works only with |
| A. | both D and E MOSFETs |
| B. | neither D nor E MOSFETs |
| Answer» B. neither D nor E MOSFETs | |
| 243. |
For an I/p of Vs = 5 sin ωt (assuming ideal diode), circuit shown in the figure will behave as a |
| A. | clipper, sine wave clipped at -2 V |
| B. | clamper, sine wave clamped at -2 V |
| C. | clamper, sine wave clamped at 0 volts |
| D. | clipper, sine wave clipped at 2 V |
| Answer» E. | |
| 244. |
In a P-N-P transistor, with normal bias, the emitter junction |
| A. | is always reverse biased |
| B. | offers very high resistance |
| C. | offers a low resistance |
| D. | remains open |
| Answer» D. remains open | |
| 245. |
Self bias is an example of __________ feedback that tends to stabilize the drain current against changes in temperature and JFET replacement. |
| A. | variable |
| B. | low |
| C. | negative |
| D. | positive |
| Answer» D. positive | |
| 246. |
Which class of amplifiers operates with least distortion? |
| A. | Class A |
| B. | Class B |
| C. | Class C |
| D. | Class AB |
| Answer» B. Class B | |
| 247. |
In following figure find VDSQ by assuming gate current is negligible for the p-channel JFET. (if IDQ = - 6 mA, RS = 0, VDD = -18 V, RD = 2 kΩ, IDSS = - 10 mA, IPO = - 3 V) |
| A. | 4 V |
| B. | - 6 V |
| C. | - 10 V |
| D. | 6 V |
| Answer» C. - 10 V | |
| 248. |
For a transistor amplifier with self biasing network, the following components are used. R1 = 4 kΩ, R2 = 4 kΩ, RC = 1 kΩ. The approximate value of the stability factor 'S' will be |
| A. | 2 |
| B. | 1.5 |
| Answer» C. | |
| 249. |
The maximum theoretical efficiency for class A amplifier is |
| A. | 0.5 |
| B. | 0.75 |
| Answer» C. | |
| 250. |
In a feedback series regular circuit, the output voltage is regulated by controlling the |
| A. | magnitude of the I/P voltage |
| B. | gain of the feed back BJT |
| C. | reference Voltage |
| D. | voltage drop across the series pass transistor |
| Answer» E. | |