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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.
| 951. |
In a CE amplifier it is desired that the signal should be able to swing equally in both directions. Then the Q point should be |
| A. | at the centre of ac load line |
| B. | at the centre of dc load line |
| C. | at the centre of collector voltage |
| D. | at the centre of collector current |
| Answer» B. at the centre of dc load line | |
| 952. |
If input ac is 10 Vrms, then maximum voltage that will appear across the diode of a half wave rectifier with a capacitor I/P filter will be |
| A. | 10 V |
| B. | 14 V |
| C. | 20 V |
| D. | 28 V |
| Answer» C. 20 V | |
| 953. |
Which of the following circuits can operate class AB for audio power output? |
| A. | Emitter follower |
| B. | Push pull |
| C. | Cascade |
| D. | Darlington pair |
| Answer» E. | |
| 954. |
To bypass a 100 ohm emitter resistor at |
| A. | 10 μF |
| B. | 100 μF |
| C. | 1000 μF |
| D. | 1 μF |
| Answer» D. 1 ŒºF | |
| 955. |
A differentiating amplifier has capacitor in the input path. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 956. |
Which of the amplifier circuits using junction transistors has the best gain? |
| A. | Common emitter |
| B. | Common base |
| C. | Common collector |
| D. | All above has the same gain |
| Answer» B. Common base | |
| 957. |
The transistor of following figure in Si diode with a base current of 40 μA and ICBO = 0, if VBB = 6V, RE = 2 kΩ and β = 90, IBQ = 20 μA then RB = |
| A. | 200 kΩ |
| B. | 265 kΩ |
| C. | 150 kΩ |
| D. | 100 kΩ |
| Answer» C. 150 kŒ© | |
| 958. |
In CE circuit the parameter f12 is very small. |
| A. | 1 |
| B. | |
| C. | JFET amplifier |
| D. | MOSFET amplifier |
| Answer» B. | |
| 959. |
In CB amplifier the distortion of the input voltage waveform may occur due to |
| A. | very low input resistance of an amplifier |
| B. | very high input resistance of the amplifier |
| C. | improper biasing |
| D. | ripples in power supply |
| Answer» B. very high input resistance of the amplifier | |
| 960. |
The ac collector current is nearly equal to |
| A. | ac base current |
| B. | ac signal current |
| C. | ac supply current |
| D. | ac emitter current |
| Answer» E. | |
| 961. |
A transistor has two p-n junctions. The batteries should be connected such that |
| A. | both junctions are forward biased |
| B. | both junctions are reverse biased |
| C. | one junction is forward biased and the other is reverse biased |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 962. |
Which op-amp circuit uses a capacitor in series with input and resistance in feedback path? |
| A. | Differentiating amplifier |
| B. | Integrating amplifier |
| C. | Logarithmic amplifier |
| D. | None of the above |
| Answer» B. Integrating amplifier | |
| 963. |
The signal input to a given amplifier is made up of 100 mΩ signal power and 1 mΩ noise power. The amplifier contributes an additional 100 mΩ of noise and has a power gain of 20 dB. The input signal-to noise ratio is |
| A. | 2 |
| B. | 10 |
| C. | 20 |
| D. | 100 |
| Answer» E. | |
| 964. |
In a JFET, gates are always |
| A. | forward biased |
| B. | reverse biased |
| C. | either forward or reverse biased |
| D. | unbiased |
| Answer» C. either forward or reverse biased | |
| 965. |
Transformer coupling in transistor amplifier circuits provides high efficiency, because |
| A. | d.c. resistance is low |
| B. | collector voltage is stepped up |
| C. | flux linkages are incomplete |
| D. | all of the above |
| Answer» B. collector voltage is stepped up | |
| 966. |
The circuit shown is |
| A. | voltage series feedback amplifier |
| B. | transconductance amplifier |
| C. | transresistance amplifier with open circuit mutual resistance RF |
| D. | transresistance amplifier with short circuit mutual resistance RF |
| Answer» D. transresistance amplifier with short circuit mutual resistance RF | |
| 967. |
Which of the following can be used as a buffer amplifier? |
| A. | CE |
| B. | CC |
| C. | CB |
| D. | Both (a) and (c) |
| Answer» C. CB | |
| 968. |
2N 2430 could be a |
| A. | semi-conductor diode |
| B. | dual gate MOSFET |
| C. | BJT |
| D. | UJT |
| Answer» D. UJT | |
| 969. |
Which of the following best represents the output impedance of an actual op-amp? |
| A. | 10 ohm |
| B. | 100 ohm |
| C. | 10 k ohm |
| D. | 100 k ohm |
| Answer» C. 10 k ohm | |
| 970. |
The transconductance curve of a JFET is |
| A. | a straight line |
| B. | parabolic |
| C. | hyperbolic |
| D. | inverted V-type |
| Answer» C. hyperbolic | |
| 971. |
The inverting op-amp shown in the figure has an open loop gain to 100. The closed loop given is |
| A. | -8 |
| B. | -9 |
| C. | -10 |
| D. | -11 |
| Answer» E. | |
| 972. |
Thermal run away of a transistor occurs when |
| A. | heat dissipation from transistor is excessive |
| B. | transistor joints melt due to high temperature |
| C. | there is excessive leakage current due to temperature rise |
| D. | none of the above |
| Answer» D. none of the above | |
| 973. |
In figure the current through resistor R |
| A. | is always equal to 130 mA |
| B. | may vary between 130 mA and 10 mA |
| C. | may vary between 65 mA and 10 mA |
| D. | is always equal to 65 mA |
| Answer» B. may vary between 130 mA and 10 mA | |
| 974. |
If the thermal resistance of a transistor is lower it means |
| A. | higher junction temperature |
| B. | lower junction temperature |
| C. | higher or lower junction temperature depending on circuit conditions |
| D. | higher or lower junction temperature depending on transistor |
| Answer» C. higher or lower junction temperature depending on circuit conditions | |
| 975. |
Efficiency of a half wave diode rectifier is less than 40%. |
| A. | 1 |
| B. | |
| C. | open loop |
| D. | closed loop |
| Answer» B. | |
| 976. |
A half wave diode rectifier has a capacitance input filter. If input voltage is Vm sin ωt, PIV is |
| A. | Vm |
| B. | 2 Vm |
| C. | 3 Vm |
| D. | 4 Vm |
| Answer» C. 3 Vm | |
| 977. |
A certain transistor has adc of 0.98 and a collectors leakage current of 5 μA. If IE = 1 mA, the base current will be |
| A. | 35 μA |
| B. | 25 μA |
| C. | 15 μA |
| D. | 5 μA |
| Answer» D. 5 ŒºA | |
| 978. |
In a common Emitter BJT amplifier, the maximum usable supply voltage is limited by |
| A. | avalanche breakdown of Base emitter junction |
| B. | collector to Base Breakdown voltage with emitter open (βVCBO) |
| C. | collector Emitter Breakdown voltage with base open (βVCBO) |
| D. | zener breakdown voltage of the emitter base Junction |
| Answer» E. | |
| 979. |
When Z1 |
| A. | inverting amplifier |
| B. | Schmitt trigger |
| C. | non-inverting amplifier |
| D. | source follower |
| Answer» E. | |
| 980. |
Saturation of iron core causes distortion. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 981. |
The input resistance of JFET ideally approaches |
| A. | zero |
| B. | 1 ohm |
| C. | 100 ohm |
| D. | infinity |
| Answer» E. | |
| 982. |
In a self bias circuit for CE amplifier, an increase in emitter resistance RE results in |
| A. | increase in emitter voltage |
| B. | decrease in emitter voltage |
| C. | increase in emitter current |
| D. | decrease in emitter current |
| Answer» E. | |
| 983. |
Which configuration has high input impedance and low output impedance? |
| A. | CB |
| B. | CE |
| C. | CC |
| D. | CB and CE |
| Answer» D. CB and CE | |
| 984. |
A 120 V, 30 Hz source feeds a half wave rectifier circuit through a 4 : 1 step down transformer, the average output voltage is |
| A. | 30 V |
| B. | 13.5 V |
| C. | 10 V |
| D. | 7.07 V |
| Answer» C. 10 V | |
| 985. |
How many cascaded stage of CE amplifiers will result in polarity inversion of the input signal? |
| A. | Two |
| B. | Three |
| C. | Four |
| D. | None |
| Answer» C. Four | |
| 986. |
Two 3Ω speakers in series will have a total impedance of |
| A. | 1 Ω |
| B. | |
| C. | 3 Ω |
| Answer» C. 3 Œ© | |
| 987. |
A certain transistor has adc of 0.98 and a collectors leakage current of 5 μA. If IE = 1 mA, the collector current will be |
| A. | 1.005 mA |
| B. | 0.985 mA |
| C. | 0.975 mA |
| D. | 0.955 mA |
| Answer» C. 0.975 mA | |
| 988. |
The units of transistor h parameters h11 and h22 are the same. |
| A. | 1 |
| B. | |
| C. | oscillators |
| D. | thyristors |
| Answer» C. oscillators | |
| 989. |
In saturation region JFET acts like a |
| A. | bipolar device |
| B. | short circuit |
| C. | switch |
| D. | resistance |
| Answer» E. | |
| 990. |
Which of the following uses a capacitor in the feedback path? |
| A. | Active low pass filter |
| B. | Active high pass filter |
| C. | Both (a) or (b) |
| D. | Neither (a) nor (b) |
| Answer» B. Active high pass filter | |
| 991. |
The purpose of using negative feedback in a op-amps is to |
| A. | stabilize overall gain |
| B. | increase output |
| C. | stabilize overall gain and increase output |
| D. | increase output and decrease input |
| Answer» B. increase output | |
| 992. |
A transistor is said to be in a quiescent state when |
| A. | the amplitude of input and output signal is equal |
| B. | the phase of input and output signal is identical |
| C. | no signal is applied to the input |
| D. | the transistor is unbiased |
| Answer» D. the transistor is unbiased | |
| 993. |
At midband frequencies the coupling capacitor in RC coupled CE amplifier may be considered as |
| A. | open circuit |
| B. | short circuit |
| C. | a reactance equal to load resistance |
| D. | none of the above |
| Answer» C. a reactance equal to load resistance | |
| 994. |
In a crystal oscillator of the Colpitt's oscillator type, the crystal is put is place of the |
| A. | resistor R1 |
| B. | condenser C2 |
| C. | condenser C1 |
| D. | inductor L |
| Answer» E. | |
| 995. |
In a class C power amplifier the input signal has a frequency of 250 kHz. If the collector current pulses are 0.1 μs wide, the duty cycle of current waveform is |
| A. | 0.5 |
| B. | 0.25 |
| C. | 0.025 |
| D. | 0.0025 |
| Answer» D. 0.0025 | |
| 996. |
Which of the following statement is incorrect? |
| A. | UJT is a 3-terminal diode having two unequally doped regions |
| B. | A UJT can be triggered by any one of its three terminals |
| C. | The bi-directional switching characteristics of a diac are symmetrical |
| D. | As compared to JFETs, MOSFETs generate less noise in high gain amplifiers |
| Answer» E. | |
| 997. |
In a tuned class C power amplifier the quiescent value of collector to emitter voltage is equal to (VCC denotes collector battery voltage) |
| A. | VCC |
| B. | 0.5 VCC |
| C. | 0.25 VCC |
| D. | either (b) or (c) |
| Answer» B. 0.5 VCC | |
| 998. |
In figure base current is 10 μA and βdc = 100. Then VE = |
| A. | 5 V |
| B. | 10 V |
| C. | 15 V |
| D. | 20 V |
| Answer» D. 20 V | |
| 999. |
In a one pole active low pass filter, the cut off frequency is fc. Then |
| A. | gain decreases at the rate of 20 dB per decade increase in frequency above fc |
| B. | gain decreases at the rate of 20 dB per decade decrease in frequency below fc |
| C. | gain decreases at the rate of 40 dB per decade increase in frequency above fc |
| D. | gain decreases at the rate 40 dB per decade decrease in frequency below fc |
| Answer» B. gain decreases at the rate of 20 dB per decade decrease in frequency below fc | |
| 1000. |
In figure v1 = 8 V and v2 = 8 V. Which diode will conduct? |
| A. | D1 only |
| B. | D2 only |
| C. | Both D1 and D2 |
| D. | Neither D1 nor D2 |
| Answer» D. Neither D1 nor D2 | |