MCQOPTIONS
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MCQOPTIONS
This section includes 2171 Mcqs, each offering curated multiple-choice questions to sharpen your ENGINEERING SERVICES EXAMINATION (ESE) knowledge and support exam preparation. Choose a topic below to get started.
| 2101. |
Positive feedback is mainly used in |
| A. | oscillators |
| B. | thyristors |
| C. | voltage regulators |
| D. | both (a) and (b) |
| Answer» E. | |
| 2102. |
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 | |
| 2103. |
Assertion (A): In class C amplifier the efficiency is more than that for other classes of amplifiersReason (R): In class C amplifier we can get high efficiency over a wideband |
| 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 | |
| 2104. |
Typical values of voltage gain for CE, CB and CC amplifiers are |
| A. | 100, 100 and 1 respectively |
| B. | 100, 1 and 100 respectively |
| C. | 100, 1 and 1 respectively |
| D. | 1, 100 and 100 respectively |
| Answer» B. 100, 1 and 100 respectively | |
| 2105. |
Which of the following plot can be directly used to determine β? |
| A. | VCE versus iC for constant IB |
| B. | VBE versus iB for constant VCE |
| C. | VCB versus iC for constant IB |
| D. | All of the above |
| Answer» B. VBE versus iB for constant VCE | |
| 2106. |
Maximum efficiency of class B power amplifier is 50%. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» C. May be True or False | |
| 2107. |
The input resistance R, of an ideal voltage amplifier is __________ and that of a current amplifier is __________ . |
| A. | zero, zero |
| B. | infinite, infinite |
| C. | zero, infinite |
| D. | infinite, zero |
| Answer» E. | |
| 2108. |
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 | |
| 2109. |
In a resistance loaded amplifier, the gain decreases at high frequencies because |
| A. | decreasing reactance of the stray CT |
| B. | increasing reactance of the stray CT |
| C. | increasing reactance of CT |
| D. | decreasing reactance of CT |
| Answer» B. increasing reactance of the stray CT | |
| 2110. |
In a N-P-N transistor the function of the emitter is |
| A. | to emit or inject holes into the collector |
| B. | to emit or inject electrons into the collector |
| C. | to emit or inject electrons into the base |
| D. | to emit or inject holes into the base |
| Answer» D. to emit or inject holes into the base | |
| 2111. |
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 | |
| 2112. |
The units of q/KT are |
| A. | V |
| B. | V¯¹ |
| C. | J |
| D. | J/K |
| Answer» C. J | |
| 2113. |
The input voltage for starting oscillations in an oscillator is caused by |
| A. | negative feedback |
| B. | positive feedback |
| C. | noise voltage in resistors |
| D. | a special generator |
| Answer» D. a special generator | |
| 2114. |
The feedback resistance rd in small signal model of MOSFET is of the order of |
| A. | 1000 MΩ |
| B. | 1 MΩ |
| C. | 1 KΩ |
| D. | 100 Ω |
| Answer» B. 1 MΩ | |
| 2115. |
When the ac base voltage in a CE amplifier circuit is too high, the ac emitter current is |
| A. | zero |
| B. | constant |
| C. | alternating |
| D. | distorted |
| Answer» E. | |
| 2116. |
In high frequency region, an amplifier behaves like a |
| A. | band pass filter |
| B. | low pass filter |
| C. | high pass filter |
| D. | any of the above |
| Answer» C. high pass filter | |
| 2117. |
An increase in ambient temperature means that maximum power rating of transistor |
| A. | will increase |
| B. | will decrease |
| C. | may increase or decrease |
| D. | may increase or remain the same |
| Answer» C. may increase or decrease | |
| 2118. |
In figure VCE (sat) = 0.1 V. Then IC (sat) = |
| A. | 10 mA |
| B. | 20 mA |
| C. | 30 mA |
| D. | 40 mA |
| Answer» C. 30 mA | |
| 2119. |
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 | |
| 2120. |
It has been found that in a rectifier circuit with RC filter one RC section reduces ripple by 15%. Two RC sections are used in cascade the reduction in ripple would be |
| A. | 15% |
| B. | 30% |
| C. | 150% |
| D. | 225% |
| Answer» E. | |
| 2121. |
A voltage tripler circuit and voltage quadrupler circuit use identical components. Then |
| A. | voltage regulation in both circuits will be same |
| B. | voltage regulation in both may or may not be same |
| C. | voltage regulation in quadrupler circuit will be better than in tripler circuit |
| D. | voltage regulation in quadrupler circuit will be poorer than in tripler circuit |
| Answer» E. | |
| 2122. |
Which circuit has its output signal from, the emitter? |
| A. | Common base |
| B. | Common emitter |
| C. | Emitter follower |
| D. | None of the above |
| Answer» D. None of the above | |
| 2123. |
Stability factor for S is given by for a fixed bias |
| A. | 1 + β |
| B. | 1 - β |
| C. | 1/β |
| D. | β - 1 |
| Answer» B. 1 - β | |
| 2124. |
Zero bias works only with |
| A. | D MOSFETs |
| B. | E MOSFETs |
| C. | both D and E MOSFETs |
| D. | neither D nor E MOSFETs |
| Answer» B. E MOSFETs | |
| 2125. |
The stray capacitance between the last stage and the first stage of an oscillator may cause |
| A. | unwanted low frequency oscillations |
| B. | unwanted high frequency oscillations |
| C. | unwanted oscillations at low and high frequencies |
| D. | large feedback |
| Answer» C. unwanted oscillations at low and high frequencies | |
| 2126. |
In a transistor CE mode, VCC = +30 V. If the transistor is in cut off region, VCE = |
| A. | +30 V |
| B. | +20 V |
| C. | 10 V |
| D. | zero |
| Answer» B. +20 V | |
| 2127. |
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 | |
| 2128. |
Volt equivalent temperature in a PN Junction diode is |
| A. | T / 11600 |
| B. | T / 1000 |
| C. | 11600 / T |
| D. | 11600 T |
| Answer» B. T / 1000 | |
| 2129. |
A silicon sample A is doped with 10¹⁸ Atoms/cm³ of Boron. Another sample B of identical dimensions is doped with 10¹⁸ atoms/cm³ of phosphorus. The ratio of electron to hole mobility is 3. The ratio of conductivity of the sample A to B is |
| A. | 3 |
| B. | 1/3 |
| C. | 2/3 |
| D. | 3/2 |
| Answer» C. 2/3 | |
| 2130. |
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 | |
| 2131. |
The horizontal intercept of dc load line is the same as ideal |
| A. | cut off point |
| B. | saturation point |
| C. | operating point |
| D. | quasi saturation point |
| Answer» B. saturation point | |
| 2132. |
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 | |
| 2133. |
Which of the following circuit has the greatest bandwidth? |
| A. | fr = 455 MHz; Q = 10 |
| B. | fr = 455 MHz; Q = 100 |
| C. | fr = 1 MHz; Q = 100 |
| D. | fr = 1 MHz; Q = 10 |
| Answer» E. | |
| 2134. |
In figure, VEB = 0.6 V, β = 99. Then VC and IC are |
| A. | 9.3 V and 1.98 mA respectively |
| B. | 4.6 V and 1.98 mA respectively |
| C. | 9.3 V and 0.02 mA respectively |
| D. | 4.6 V and 0.02 mA respectively |
| Answer» B. 4.6 V and 1.98 mA respectively | |
| 2135. |
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 kΩ | |
| 2136. |
The output V0 in figure is |
| A. | -100 V |
| B. | -100 mV |
| C. | 10 V |
| D. | 10 mV |
| Answer» C. 10 V | |
| 2137. |
In the amplifier circuit of figure hfe = 100 and hie = 1000 Ω. The voltage gain of amplifier is about |
| A. | 0.33 |
| B. | 0.5 |
| C. | 0.66 |
| D. | 1 |
| Answer» E. | |
| 2138. |
In oscillators class C operation is preferred because |
| A. | is most efficient |
| B. | has frequency stability |
| C. | gives larger output |
| D. | it produces nearly square waves |
| Answer» E. | |
| 2139. |
In figure the cut in voltage of diode is 0.7 V and its bulk resistance is 20 Ω. The peak value of circuit current of during positive and negative half cycles are |
| A. | 10 mA and zero |
| B. | 9.12 mA and zero |
| C. | 9.3 mA and zero |
| D. | zero and 9.12 mA |
| Answer» C. 9.3 mA and zero | |
| 2140. |
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° | |
| 2141. |
In which amplifier circuit is gate conductance negligible? |
| A. | JFET amplifier |
| B. | MOSFET amplifier |
| C. | Both JFET and MOSFET amplifier |
| D. | None of the above |
| Answer» C. Both JFET and MOSFET amplifier | |
| 2142. |
The input impedance of op-amp circuit of figure is |
| A. | 120 k ohm |
| B. | 110 k ohm |
| C. | infinity |
| D. | 10 k ohm |
| Answer» E. | |
| 2143. |
In figure vi = 10 mV dc maximum. The maximum possible dc output offset voltage is |
| A. | 60 mV dc |
| B. | 110 mV dc |
| C. | 130 mV dc |
| D. | 150 mV dc |
| Answer» C. 130 mV dc | |
| 2144. |
In following circuit, RB will be if VCC = 10 V, VS = 2 V, RC = 5 kΩ, RS = 90 kΩ, β = 50, ICE = 0, VCEsat = 0.1 V |
| A. | 230 K |
| B. | 235 K |
| C. | 240 K |
| D. | 250 K |
| Answer» C. 240 K | |
| 2145. |
Assertion (A): A class C amplifier is a timed amplifier which needs a tank circuit as the load in the collector circuit of the transistor for its proper operationReason (R): In class C operation collector current flows for less than 180° of the ac cycle and thus flows in pulses |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 2146. |
Assertion (A): For large signal variations an amplifier circuit has to be analysed graphicallyReason (R): The output characteristics of a transistor is nonlinear. |
| 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» B. Both A and R are correct but R is not correct explanation for A | |
| 2147. |
Assertion (A): In an op-amp the voltage gain and band width can be adjusted as per requirementReason (R): Large value capacitor can also be fabricated on a chip |
| 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 | |
| 2148. |
The phase angle of lead circuit is |
| A. | between 0 and -90° |
| B. | between 0 and +90° |
| C. | 90° |
| D. | more than 90° |
| Answer» C. 90° | |
| 2149. |
In a combination limiter with sinusoidal input voltage the output wave can be nearly square. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 2150. |
The approximate value of input impedance of a common emitter amplifier with emitter resistance Re is given by |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |