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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.
| 801. |
In a bipolar transistor at room temperature if the emitter current is doubled the voltage across its base emitter junction |
| A. | doubles |
| B. | halves |
| C. | increase by about 20 mV |
| D. | decrease by about 20 mV |
| Answer» C. increase by about 20 mV | |
| 802. |
An engineer designs an amplifier to have a voltage gain of 60, but when constructed it only had a gain of 50. What percentage of feedback will cause oscillations? |
| A. | 0.001 |
| B. | 0.005 |
| C. | 0.01 |
| D. | 0.02 |
| Answer» E. | |
| 803. |
In the graphical analysis of CE amplifier circuit, the intersection of base current and dc load line is called |
| A. | saturation point |
| B. | cut off point |
| C. | Q point |
| D. | operating point |
| Answer» D. operating point | |
| 804. |
Which junction transistor is preferred for high input and low output impedances? |
| A. | Common emitter |
| B. | Common base |
| C. | Common collector |
| D. | Any of the above |
| Answer» D. Any of the above | |
| 805. |
Leakage current approximately doubles for every 10°C increase in the temperature of a transistor has ICBO = 400 nA at 25°C, then its leakage current at 80°C |
| A. | 10 μA |
| B. | 18 μA |
| C. | 20 μA |
| D. | 15 μA |
| Answer» C. 20 ŒºA | |
| 806. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The input voltage to the amplifier is |
| A. | 0.1 m V |
| B. | 0.4 m V |
| C. | 1 m V |
| D. | 4 m V |
| Answer» C. 1 m V | |
| 807. |
In a combination limiter with sinusoidal input voltage the output wave can be nearly square. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 808. |
The circuit of figure is |
| A. | positive clipper |
| B. | negative clipper |
| C. | combination clipper |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 809. |
The slope of the transfer characteristics of an N-channel JFET is |
| A. | positive |
| B. | negative |
| C. | constantly varying |
| D. | zero |
| Answer» C. constantly varying | |
| 810. |
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-off region |
| D. | inverted region |
| Answer» B. saturation region | |
| 811. |
Turn on time of a transistor switch is equal to sum of (where tr is rise time, td is delay time) |
| A. | ts - tr |
| B. | ts - tf |
| C. | td + tr |
| D. | 2tr |
| Answer» D. 2tr | |
| 812. |
With negative feedback the closed loop gain is always less than open loop gain. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 813. |
In rectifiers the use of RC filters is recommended when |
| A. | load current is high |
| B. | load current is small |
| C. | load current is neither high nor small |
| D. | either (a) or (c) |
| Answer» C. load current is neither high nor small | |
| 814. |
The main disadvantage of a JFET is |
| A. | low gain-bandwidth product |
| B. | high noise level |
| C. | high cost |
| D. | low gain |
| Answer» B. high noise level | |
| 815. |
A Darlington pair has β = 300. If RE = 1 kΩ and RL = 100 Ω, the input impedance at the base is approximately |
| A. | 300 k ohm |
| B. | 3 k ohm |
| C. | 100 k ohm |
| D. | 30 k ohm |
| Answer» C. 100 k ohm | |
| 816. |
Assertion (A): A resistor is a passive load and a transistor is an active loadReason (R): Op-amp is mostly used in feedback mode |
| 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» C. A is correct R is wrong | |
| 817. |
In a class C operation VCC = 40 V, RL = 50 Ω. The maximum load power can be |
| A. | 64 W |
| B. | 32 W |
| C. | 16 W |
| D. | 8 W |
| Answer» D. 8 W | |
| 818. |
In figure, ID = 4 mA. Then VDS = |
| A. | 20 V |
| B. | 16 V |
| C. | 4 V |
| D. | 0.4 V |
| Answer» D. 0.4 V | |
| 819. |
In all base driver amplifiers |
| A. | ac collector voltage is 180° out of phase with ac base voltage |
| B. | ac emitter voltage is 180° out of phase with ac base voltage |
| C. | ac collector voltage is in phase with ac base voltage |
| D. | none of the above |
| Answer» B. ac emitter voltage is 180¬∞ out of phase with ac base voltage | |
| 820. |
The D.C. alpha(a) of a transistor is approximately |
| A. | unity |
| B. | 10 to 50 |
| C. | 100 to 500 |
| D. | 1000 to 5000 |
| Answer» B. 10 to 50 | |
| 821. |
The current flowing in a certain P-N junction at room temperature is 2 x 10-7 Amp. When a large reverse biased voltage is applied. Calculate the current flowing when 0.1 volts is applied. |
| A. | 9 μA |
| B. | 10 μA |
| C. | 2 μA |
| D. | 4 μA |
| Answer» B. 10 ŒºA | |
| 822. |
In a self bias circuit for CE amplifier the collector supply voltage is made twice. The collector current will |
| A. | decrease |
| B. | increase |
| C. | remain the same |
| D. | increase or decrease |
| Answer» C. remain the same | |
| 823. |
Efficiency of class A power amplifier is very poor. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 824. |
A full wave bridge diode rectifier uses diodes having forward resistance of 50 ohms each. The load resistance is also 50 ohms. The voltage regulations is |
| A. | 0.2 |
| B. | 0.5 |
| C. | 1 |
| D. | 2 |
| Answer» E. | |
| 825. |
Two CE stages are coupled through a capacitor. To calculate the quiescent base current of the two transistors, the capacitor is treated as |
| A. | open circuit |
| B. | short circuit |
| C. | neither (a) nor (b) |
| D. | either (a) or (b) |
| Answer» B. short circuit | |
| 826. |
A BJT is said to be operating in saturation region if |
| A. | both junctions are reverse biased |
| B. | both junctions are forward biased |
| C. | base emitter junction is forward biased and base collector junction is reverse biased |
| D. | base collector junction is forward biased and base emitter junction is reverse biased |
| Answer» C. base emitter junction is forward biased and base collector junction is reverse biased | |
| 827. |
Assertion (A): Class A and Class B amplifier predominate in audio applications.Reason (R): Class C amplifier is used at radio frequencies. |
| 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» C. A is correct R is wrong | |
| 828. |
In common base amplifier the current gain is less than one, but the voltage gain may be anywhere from |
| A. | 0.5 to 1 |
| B. | 1 to 5 |
| C. | 5 to 10 |
| D. | 50 to 2000 |
| Answer» E. | |
| 829. |
If input frequency is 50 Hz, the frequency of output wave in a full wave diode rectifier circuit is |
| A. | 25 Hz |
| B. | 50 Hz |
| C. | 100 Hz |
| D. | 200 Hz |
| Answer» D. 200 Hz | |
| 830. |
In figure what is the base current if VBE = 0.7 V |
| A. | 10 mA |
| B. | 9.3 mA |
| C. | 10 μA |
| D. | 9.3 μA |
| Answer» E. | |
| 831. |
The circuit diagram shown in the figure consists of transistors in; |
| A. | parallel connection |
| B. | cascade connection |
| C. | darlington connection |
| D. | series connection |
| Answer» B. cascade connection | |
| 832. |
In a self bias circuit for CE amplifier, the base voltage is |
| A. | equal to supply voltage |
| B. | more than supply voltage |
| C. | equal to or more than supply voltage |
| D. | less than supply voltage |
| Answer» E. | |
| 833. |
In the circuit figure LED will be on when v1 is |
| A. | less than 6 V |
| B. | more than 6 V |
| C. | less than 12 V |
| D. | more than 12 V |
| Answer» C. less than 12 V | |
| 834. |
In a practical oscillator, the magnitude of loop gain Aβ is kept slightly larger than unity and the amplitude of oscillations is limited by |
| A. | the ratio of A to β |
| B. | the on set of non-linearity of amplifying device |
| C. | the linearity of amplifying device |
| D. | all of the above |
| Answer» C. the linearity of amplifying device | |
| 835. |
Power transistors are invariably provided with |
| A. | soldered connections |
| B. | heat sink |
| C. | metallic casing |
| D. | none of the above |
| Answer» C. metallic casing | |
| 836. |
In a class C amplifier, full cycle conductor of the current is achieved by employing |
| A. | tuned circuit |
| B. | transformers |
| C. | complementary pair |
| D. | Push pull configuration |
| Answer» B. transformers | |
| 837. |
The dissipation at the collector is in the quiescent state and increases with excitation in the case of a |
| A. | class A series fed Amplifier |
| B. | class A transistor coupled Amplifier |
| C. | class AB amplifier |
| D. | class B amplifier |
| Answer» E. | |
| 838. |
Which of the following is the fastest switching device? |
| A. | JFET |
| B. | BJT |
| C. | MOSFET |
| D. | Triode |
| Answer» D. Triode | |
| 839. |
In a BJT amplifier circuit the size of coupling capacitor depends on |
| A. | lowest frequency |
| B. | highest frequency |
| C. | average of lowest and highest frequencies |
| D. | none of the above |
| Answer» B. highest frequency | |
| 840. |
FET can used in |
| A. | buffer amplifier circuits |
| B. | cascade amplifier circuits |
| C. | digital circuits |
| D. | all of the above |
| Answer» B. cascade amplifier circuits | |
| 841. |
In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is |
| A. | 30 V |
| B. | 60 V |
| C. | 15 V |
| D. | 10 V |
| Answer» C. 15 V | |
| 842. |
A CE amplifier is the most common BJT amplifier. |
| A. | 1 |
| B. | |
| C. | two low gain at low frequency |
| D. | poor phase response |
| Answer» B. | |
| 843. |
A full wave rectifier circuit using centre tapped transformer, the input frequency 50 Hz. The frequency of output is |
| A. | 100 Hz |
| B. | 50 Hz |
| C. | 25 Hz |
| D. | none of the above |
| Answer» B. 50 Hz | |
| 844. |
In a CE amplifier the output coupling capacitor is short circuited. The dc collector voltage |
| A. | will increase |
| B. | may increase or decrease |
| C. | will remain the same |
| D. | will decrease |
| Answer» E. | |
| 845. |
An amplifier has input impedance of 4 kΩ and output impedance of 80 kΩ. It is used in negative feedback circuit with 10% feedback. If open loop gain is 90, the closed loop input and output impedances are |
| A. | 40 kΩ and 8 kΩ respectively |
| B. | 4 kΩ and 80 kΩ respectively |
| C. | 0.4 kΩ and 800 kΩ respectively |
| D. | 8 kΩ and 160 kΩ respectively |
| Answer» B. 4 kŒ© and 80 kŒ© respectively | |
| 846. |
Assertion (A): A common collector amplifier is used for matching a high impedance source to a low impedance loadReason (R): A common collector amplifier has a near unity voltage gain |
| 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» C. A is correct R is wrong | |
| 847. |
When negative feedback is used the fractional changes in closed loop gain are desensitized by the factor (1 + Avβ) |
| A. | 1 |
| B. | |
| C. | In a JFET, gate and source have opposite polarity with respect to drain irrespective of the type of FET |
| D. | In its schematic symbol for JFET, the arrow always points to p-type material |
| Answer» B. | |
| 848. |
A clamper |
| A. | adds a dc component to the input signal |
| B. | removes signal voltages above or below a specified value |
| C. | both (a) and (b) |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 849. |
Which of the following? |
| A. | Voltage series feedback and decrease I/P impedance. |
| B. | Voltage shunt feedback and decrease I/P impedance. |
| C. | Voltage series feedback and increase I/P impedance. |
| D. | Voltage shunt feedback and increase I/P impedance. |
| Answer» D. Voltage shunt feedback and increase I/P impedance. | |
| 850. |
In figure as the load resistance is changed |
| A. | the zener current remain constant |
| B. | the load current remains constant |
| C. | the output voltage remains constant |
| D. | the output voltage and current through R remain constant |
| Answer» E. | |