InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Ac signals are given to both inverting and non-inverting terminals of an op-amp. When will the output maximum |
| Answer» For non-inverting terminal input, output is in phase with input. For inverting terminal input, output is 180° out of phase with input. If inputs have 180° phase difference, outputs will be in phase and additive. | |
| 52. |
In a self bias circuit for CE amplifier, the emitter resistance is made three times the original value. The collector current will |
| Answer» The emitter current becomes one-third since collector current in BJT is almost the same as emitter current, collector current also becomes one-third. | |
| 53. |
A P-channel MOSFET operating in the enhancement mode is characterized by V = - 4 V and I = - 10 mA, when V = - 5.5 V, what will be V if I = -15 mA and I = - 16 mA |
| Answer» . | |
| 54. |
For dc the current through coupling capacitor in CE amplifier circuit is |
| Answer» dc remains confined within BJT. Only ac signal comes out. | |
| 55. |
In a CE amplifier the collector resistance is short circuited. The ac output voltage will |
| Answer» Since the output is taken across collector resistance, short-circuiting collector resistance will decrease output voltage. | |
| 56. |
In a transistor CE mode, V = +30 V. If the transistor is in cut off region, V = |
| Answer» When transistor is in cut off region VCE = VCC . | |
| 57. |
The dc load current in a bridge rectifier circuit is 10 mA. The dc load current through each diode is |
| Answer» Since both diodes contribute equal load current, each diode current is 5 mA. | |
| 58. |
An integrating amplifier has resistance in feedback path. |
| Answer» It has capacitance in feedback path. | |
| 59. |
Figure shows a portion of linear - characteristics of diode. If applied voltage is + 6 V, the current will be |
| Answer» . | |
| 60. |
A power transistor dissipates 5 W. If ambient temperature is 30° and case to air thermal resistance is 10° C/W, the case temperature is |
| Answer» | |
| 61. |
In a transistor E mode the collector current with the transistor in cut off region is |
| Answer» When transistor is cut off, IC is zero. | |
| 62. |
Two CE stages, 1 and 2 are coupled through a capacitor. V is the same for both. Base resistances R and R are such that R > R. Then |
| Answer» Since RB2 < RB1, IB2 > IB1. | |
| 63. |
In a two stage CE amplifier circuit, the ac collector resistance of the first stage depends on |
| Answer» Since the first amplifier is feeding the second stage, the input impedance of second stage is the ac collector resistance of first stage. | |
| 64. |
In a CE amplifier the ac cut off voltage is 9 V and slope of ac load line is - 0.5 mA/V. The ac saturation current is |
| Answer» AC saturation current is cutoff voltage x slope of ac load line. | |
| 65. |
An ideal op-amp has zero slew rate. |
| Answer» An ideal op-amp has infinitely fast slew rate. | |
| 66. |
In a bridge rectifier circuit the rms value of input ac voltage is 10 V. The PIV across each diode is |
| Answer» PIV is 2 x 10 = 14.14 V. | |
| 67. |
In a half wave diode rectifier circuit the current flows in the load circuit for |
| Answer» Current flows during positive half cycle. | |
| 68. |
In a push pull circuit |
| Answer» Since each transistor conducts for 180°. Therefore high efficiency but low distortion. | |
| 69. |
The ripple factor of a half wave rectifier is more than 2. |
| Answer» Ripple factor of half wave rectifier is 1.21 . | |
| 70. |
In figure the zener current |
| Answer» When IL = 0, Zener current = 130 mA, when IL = 120 mA, zener current (t = 10 mA). | |
| 71. |
In a commercially available good power supply the voltage regulation is about |
| Answer» A good power supply does not allow output voltage to vary by more than 1% . | |
| 72. |
In the circuit of figure the diode |
| Answer» Diode will always be reverse biased. | |
| 73. |
The most commonly used bias in BJT amplifier circuits is |
| Answer» Voltage divider bias stabilizes IC. | |
| 74. |
In a CE amplifier |
| Answer» Since ac collector resistance is less than dc collector resistance, slope of ac load line is more than that of dc load line. | |
| 75. |
The voltage gain of an amplifier without and with feedback are 100 and 20. The negative feedback is |
| Answer» or β = 0.04 or 4% . | |
| 76. |
In the circuit shown in figure, R = 10k, R = 150Ω, β = 100, I = 1 mA. The value of , will be |
| Answer» circuit shown is Darlington Amplifier. Gain . | |
| 77. |
Calculate the conductivity of pure silicon at room temperature when the concentration of carriers is 1.6 x 10 per cm. Take μ = 1500 cm/V-sec, μ = 500 cm/V-sec at room temperature, |
| Answer» σi = (μe + μn) . e . ni . | |
| 78. |
A potential of 7 V is applied to a silicon diode. A resistance of 1 kΩ is also connected in series. If the diode is forward biased, the current in the circuit is |
| Answer» A = 6.3 mA. | |
| 79. |
In the circuit of figure, = = 10 V. Then |
| Answer» Current in diode D2 will be more because resistance in series with D2 is less. | |
| 80. |
In the graphical analysis of an amplifier circuit, the slope of dc load line depends on |
| Answer» Slope is . | |
| 81. |
In figure we need an ac ground. The proper value of C is |
| Answer» XC should be less than 10% of 10 kΩ. There XC < 1000 Ω. | |
| 82. |
In figure the voltage drop across diode is 0.7 V. Then the voltage across diode during negative half cycle is |
| Answer» PIV = 10 V. | |
| 83. |
In figure = 10 mV dc maximum. The maximum possible dc output offset voltage is |
| Answer» Maximum dc output offset voltage = . | |
| 84. |
In the op-amp circuit given in the figure, the load current is |
| Answer» Applying KCL [KCL at non inverting terminal] . | |
| 85. |
A CE amplifier has = 6 Ω, β = 100 and = 0.98. The input impedance is |
| Answer» Input impedance of CE amplifier is β re = 100 X 6 = 600 Ω. | |
| 86. |
A full wave diode rectifier using centre tapped transformer has diodes with forward resistance of 50 ohms each. The load resistance of 50 ohms each. The load resistance is also 50 ohms. The voltage regulation is |
| Answer» No load output voltage = Output voltage at full load = | |
| 87. |
Leakage current approximately doubles for every 10°C increase in the temperature of a transistor has I = 400 nA at 25°C, then its leakage current at 80°C |
| Answer» ICBO = (400 x 10-9) 2(80-25)/10 = 18 μA. | |
| 88. |
The inverting op-amp shown in the figure has an open loop gain to 100. The closed loop given is |
| Answer» Applying KCL inverting node . | |
| 89. |
In a voltage regulated power supply the zener operates in the breakdown region when (V is input voltage and V is zener breakdown voltage) |
| Answer» Zener breakdown when input voltage is more than zener breakdown voltage. | |
| 90. |
The dissipation at the collector is in the quiescent state and increases with excitation in the case of a |
| Answer» Only one transistor conducts without biasing. | |
| 91. |
The parameter for CB circuit is higher than that for CE circuit. |
| Answer» It is lower. | |
| 92. |
Figure shows a self bias circuit for FET amplifier, I = 4 mA. Then I = |
| Answer» Since gate current is negligible IS = ID = 4 mA. | |
| 93. |
In the CE equivalent circuit of figure, the voltage gain is |
| Answer» | |
| 94. |
The open loop gain of an ideal op-amp is |
| Answer» An ideal op-amp has infinite open loop gain. | |
| 95. |
Heat sink results in |
| Answer» Surface area of heat dissipating surface increases. Therefore heat dissipation is faster. | |
| 96. |
In an amplifier the voltage gain is the ratio of |
| Answer» Voltage gain is always the ratio of output and input voltages. | |
| 97. |
The critical frequency of the circuit of figure is |
| Answer» Critical frequency of RC circuit = . | |
| 98. |
Find resistance R to bring transistor to threshold of saturation V = 0, V = 0.7 V, = 0.96 |
| Answer» 1.5 kΩ. | |
| 99. |
In the circuit of figure diode will conduct |
| Answer» Diode will conduct when instantaneous value of ac voltage is more than 50 V. | |
| 100. |
The input to integrating op-amp is a rectangular wave. The output will be |
| Answer» Integral of constant is t. | |