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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.
| 901. |
In an amplifier the voltage gain is the ratio of |
| A. | output voltage and emitter resistance |
| B. | output voltage and input current |
| C. | output voltage and input voltage |
| D. | none of the above |
| Answer» D. none of the above | |
| 902. |
Which of the following device acts as an N-P-N and a P-N-P transistor connected base to base and emitter to controller? |
| A. | UJT |
| B. | SCR |
| C. | Diac |
| D. | Triac |
| Answer» C. Diac | |
| 903. |
In deriving ac equivalent circuit for an amplifier circuit we short circuit |
| A. | all resistors |
| B. | all transistors |
| C. | all inductors |
| D. | all capacitors |
| Answer» E. | |
| 904. |
Which of the following are difficult to be fabricated in a monolithic IC? |
| A. | Inductors |
| B. | Large capacitors |
| C. | Small capacitors |
| D. | Both (a) and (b) |
| Answer» E. | |
| 905. |
The noise figure is |
| A. | 3 dB |
| B. | 6 dB |
| C. | 6.6 dB |
| D. | 12 dB |
| Answer» B. 6 dB | |
| 906. |
In the circuit of figure diode will conduct |
| A. | from 90 to 180° in the positive half cycle |
| B. | from 30° to 180° in the positive half cycle |
| C. | from 50° to 160° in the positive half cycle |
| D. | from 30° to 150° in the positive half cycle |
| Answer» E. | |
| 907. |
In a full wave diode rectifier circuit each diode carries current for |
| A. | 90° in each cycle |
| B. | 180° in each cycle |
| C. | 270° in each cycle |
| D. | 360° in each cycle |
| Answer» C. 270¬∞ in each cycle | |
| 908. |
If the differential voltage gain and the common mode voltage gain of a differential amplifier are 48 dB and 2 dB respectively, then its common mode rejection ratio is |
| A. | 23 dB |
| B. | 25 dB |
| C. | 46 dB |
| D. | 50 dB |
| Answer» D. 50 dB | |
| 909. |
The 'h' parameters of the circuit shown in the figure are hib = 25 Ω, hfb = 0.999 and hob = 10-6Ω The Voltage gain is |
| A. | 0.99 |
| B. | 1.98 |
| C. | 2 |
| D. | 4 |
| Answer» E. | |
| 910. |
A JFET is a |
| A. | unipolar device |
| B. | bipolar device |
| C. | tripolar device |
| D. | none of the above |
| Answer» B. bipolar device | |
| 911. |
The h parameter equivalent to ac resistance re is |
| A. | hib |
| B. | hfe |
| C. | hob |
| D. | hrb |
| Answer» B. hfe | |
| 912. |
When narrow current pulses drive a high Q resonant circuit the voltage across the circuit looks like |
| A. | narrow pulses |
| B. | half sine wave |
| C. | almost sine wave |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 913. |
In a CE amplifier |
| A. | both ac and dc load lines have the same slope |
| B. | the ac load line has more slope than dc load line |
| C. | the ac load line has less slope than dc load line |
| D. | the two load lines may have slope more than the other |
| Answer» C. the ac load line has less slope than dc load line | |
| 914. |
The voltage gains of an amplifier without feedback and with negative feedback respectively are 100 and 20. The percentage of negative feedback (β) would be |
| A. | 0.4 |
| B. | 0.05 |
| C. | 0.2 |
| D. | 0.8 |
| Answer» B. 0.05 | |
| 915. |
A bridge rectifier circuit has input of 50 Hz frequency. The load resistance is RL and filter capacitance is C. For good output wave shape, the time constant RLC should be at least equal to |
| A. | 10 ms |
| B. | 20 ms |
| C. | 50 ms |
| D. | 100 ms |
| Answer» E. | |
| 916. |
For an ideal noise free transistor amplifier the noise factor is |
| A. | zero |
| B. | zero dB |
| C. | 1 dB |
| D. | depends on other factors |
| Answer» C. 1 dB | |
| 917. |
A forward voltage of 9 V is applied to a diode in series with a 1 kΩ load resistor. The voltage across load resistor is zero. It indicates that |
| A. | diode is short circuited |
| B. | diode is open circuited |
| C. | resistor is open circuited |
| D. | diode is either short circuited or open circuited |
| Answer» C. resistor is open circuited | |
| 918. |
If three cascaded stages of amplifier have gains 10, 20 and 30 the overall voltage will be |
| A. | 30 |
| B. | 60 |
| C. | 600 |
| D. | 6000 |
| Answer» E. | |
| 919. |
In a power amplifier the collector current flows for 270° of the input cycle. The operations is |
| A. | class A |
| B. | class B |
| C. | class AB |
| D. | class C |
| Answer» D. class C | |
| 920. |
Assertion (A): An op-amp has high voltage gain, high input impedance and low output impedanceReason (R): Negative feedback increases output impedance |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» D. A is wrong R is correct | |
| 921. |
The period of oscillation of a symmetrical multivibrator depends upon the discharging time constant and is roughly given by |
| A. | T = 1.4 RC |
| B. | |
| C. | T = 1.4 RC |
| Answer» B. | |
| 922. |
Which of the following statement is wrong? |
| A. | A depletion type N-channel MOSFET conducts even when VGS = 0 |
| B. | A BJT is very sensitive to radiation whereas FET is relatively immune |
| C. | Bipolars need higher supply voltage than FETs |
| D. | Both N-channel as well as p-channel JFETs work in the depletion mode |
| Answer» D. Both N-channel as well as p-channel JFETs work in the depletion mode | |
| 923. |
A Darlington circuit is obtained by connecting |
| A. | two CB stages in cascade |
| B. | two CE stages in cascade |
| C. | a CE stages followed by CB stage |
| D. | two emitter follower in cascade |
| Answer» B. two CE stages in cascade | |
| 924. |
A circuit using an op-amp is shown in the given figure. It has |
| A. | voltage series feedback |
| B. | voltage shunt feedback |
| C. | current shunt feedback |
| D. | current series feedback |
| Answer» C. current shunt feedback | |
| 925. |
The disadvantage of FET over BJT is |
| A. | poor high frequency performance |
| B. | low power-handling ability |
| C. | low values of voltage gain |
| D. | all of the above |
| Answer» E. | |
| 926. |
In a N-P-N transistor, when emitter junction is forward biased and collector junction is reverse biased, the transistor will operate in |
| A. | active region |
| B. | saturation region |
| C. | cut of region |
| D. | inverted region |
| Answer» B. saturation region | |
| 927. |
If 1.5% of the output of an amplifier is feedback positively to the input, the minimum gain required of the amplifier for oscillations to occur, is |
| A. | 16.6 |
| B. | 44.4 |
| C. | 66.6 |
| D. | 75 |
| Answer» D. 75 | |
| 928. |
Which one of the following power amplifier has the maximum efficiency? |
| A. | Class A |
| B. | Class B |
| C. | Class AB |
| D. | Class C |
| Answer» E. | |
| 929. |
An op-amp is fed from a signal source through resistance R1. If it is to work as sign changer, the feedback resistance Rf should be |
| A. | equal to R1 |
| B. | twice R1 |
| C. | half R1 |
| D. | either (b) or (c) |
| Answer» B. twice R1 | |
| 930. |
Astable multivibrator has |
| A. | one stable state |
| B. | two stable state |
| C. | two quasi-stable states |
| D. | one quasi stable state |
| Answer» D. one quasi stable state | |
| 931. |
The h parameter equivalent circuit of BJT has one voltage source and one current source. |
| A. | 1 |
| B. | |
| C. | Bias current of inverting input only |
| D. | Bias current of inverting and non-inverting inputs only |
| Answer» B. | |
| 932. |
Wien bridge uses |
| A. | lead network |
| B. | lag network |
| C. | lead-lag network |
| D. | Both (a) and (b) |
| Answer» D. Both (a) and (b) | |
| 933. |
The oscillator shown in figure is a |
| A. | Colpitt's oscillator |
| B. | Hartley oscillator |
| C. | Tuned emitter oscillator |
| D. | Clapp oscillator |
| Answer» B. Hartley oscillator | |
| 934. |
Figure shows current pulses of a class C power amplifier. The fundamental frequency of these pulses is |
| A. | 100 kHz |
| B. | 1000 kHz |
| C. | 10 kHz |
| D. | 1 kHz |
| Answer» B. 1000 kHz | |
| 935. |
In figure what is value of IC if βdc = 100. Neglect VBE |
| A. | 5 mA |
| B. | 5 μA |
| C. | 10 mA |
| D. | 10 μA |
| Answer» D. 10 ŒºA | |
| 936. |
A FET has |
| A. | very high input resistance |
| B. | very low input resistance |
| C. | high connection emitter junction |
| D. | forward biased PN junction |
| Answer» B. very low input resistance | |
| 937. |
The changes in ambient temperature affect the open loop gain of amplifier. |
| A. | 1 |
| B. | |
| C. | source, channel |
| D. | channel, drain |
| Answer» B. | |
| 938. |
For a push pull circuit the most favoured biasing method is |
| A. | self bias |
| B. | emitter bias |
| C. | diode bias |
| D. | collector bias |
| Answer» D. collector bias | |
| 939. |
The pinch-off voltage is the drain voltage on the shorted gate drain curve above which the drain current becomes |
| A. | almost negligible |
| B. | very high |
| C. | almost constant |
| D. | highly variable |
| Answer» D. highly variable | |
| 940. |
Assuming VCE sat = 0.2 V and β = 50, the minimum base current (IB) required to drive the transistor in the given figure to saturation is |
| A. | 56 μA |
| B. | 140 μA |
| C. | 60 μA |
| D. | 3 μA |
| Answer» B. 140 ŒºA | |
| 941. |
A limiter circuit can be built using a diode and resistance. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 942. |
Which of the following is not valid in case of bipolars? |
| A. | It has a low input impedance |
| B. | It has high voltage gain |
| C. | It is a current controlled device |
| D. | It is difficult to bias |
| Answer» E. | |
| 943. |
In CE amplifier |
| A. | input and output are in phase |
| B. | phase difference between input and output is 30° to 90° |
| C. | phase difference between input and output is 60° to 120° |
| D. | output is inverted with respect to its input voltage |
| Answer» E. | |
| 944. |
The ac input voltage of an amplifier |
| A. | is always equal to ac signal voltage |
| B. | may be equal to or more than ac signal voltage |
| C. | is always less than ac signal voltage |
| D. | may be equal or more or less than ac signal voltage |
| Answer» E. | |
| 945. |
In feedback amplifier the closed loop gain is nearly independent of open loop gain and depends only on the feedback factor. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 946. |
A 12 kHz pulse wave-form is amplified by a circuit having an Upper cut-off frequency of 1 MHz. The minimum input pulse width that can be accurately reproduced is |
| A. | 83.33 μ sec |
| B. | 1 μ sec |
| C. | 0.1 m sec |
| D. | 3.5 m sec |
| Answer» C. 0.1 m sec | |
| 947. |
Which of the following circuit would be preferred for a 355 KHz IF amplifier? |
| A. | Resistance loaded |
| B. | Double tuned transformer |
| C. | Video amplifier |
| D. | Class C |
| Answer» C. Video amplifier | |
| 948. |
Transformer coupling is mostly used in |
| A. | RF amplifier |
| B. | audio amplifier |
| C. | both audio and RF amplifier |
| D. | none of the above |
| Answer» D. none of the above | |
| 949. |
For a system to work, as oscillator the total phase shift of the loop gain must be equal to |
| A. | 90° |
| B. | 45° |
| C. | 270° |
| D. | 360° |
| Answer» E. | |
| 950. |
The turn ratio of a transformer is 20:1, if a load of 10Ω is connected across the secondary, what will be the effective resistance seen looking into the Primary? |
| A. | 2 kΩ |
| B. | 4 kΩ |
| C. | 8 kΩ |
| D. | 32 kΩ |
| Answer» C. 8 kŒ© | |