# Multiple choice question for engineering

## Set 1

(Q.1-Q.2) For the circuit given below i1 = 4 sin(2t) and i2 = 0

1. v1 = ?

a) -16 cos 2t V

b) 16 cos 2t V

c) 4 cos 2t V

d) -4 cos 2t V

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2. v2 = ?

a) 2 cos 2t V

b) -2 cos 2t V

c) 8 cos 2t V

d) -8 cos 2t V

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Circuit for Q.3-Q.4

3. If i1 = 0 and i2 = 2 sin(4t), the voltage v1 is

a) -24 cos(4t) V

b) 24 cos(4t) V

c) 1.5 cos(4t) V

d) -1.5 cos(4t) V

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4. If i1 = e^{(-2t)} and i2 = 0, the voltage v1 is

a) -6e^{(-2t)} V

b) 6e^{(-2t)} V

c) 1.5e^{(-2t)} V

d) -1.5e^{(-2t)} V

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Circuit for Q.5-Q.8

5. If i1 = 3 cos(4t) and and i2 = 0. Find v1.

a) -24 sin(4t) V

b) 24 sin(4t) V

c) 1.5 sin(4t) V

d) -1.5 sin(4t) V

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6. If i1 = 3 cos(4t) and and i2 = 0. Find v2.

a) -24 sin(4t) V

b) -36 sin(4t) V

c) sin(4t) V

d) -sin(4t) V

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7. If i1 = 4 cos(3t) and and i1 = 0. Find v2.

a) 12 cos(3t) V

b) -12 cos(3t) V

c) -24 cos(3t) V

d) 24 cos(3t) V

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8. If i2 = 4 cos(3t) and and i1 = 0. Find v2.

a) -12 cos(3t) V

b) -24 cos(3t) V

c) -36 cos(3t) V

d) -48 cos(3t) V

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9. Leq = ?

a) 4 H

b) 6 H

c) 7 H

d) 0 H

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10. Leq = ?

a) 2 H

b) 4 H

c) 6 H

d) 8 H

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## Set 2

1. V1 = ?

a) 0.4 Vg

b) 1.5 Vg

c) 0.67 Vg

d) 2.5 Vg

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2. Va = ?

a) -11 V

b) 11 V

c) 3 V

d) -3 V

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3. V1 = ?

a) 120 V

b) -120 V

c) 90 V

d) -90 V

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4. Va = ?

a) 4.33 V

b) 4.09 V

c) 8.67 V

d) 8.18 V

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5. V2 = ?

a) 0.5 V

b) 1.0 V

c) 1.5 V

d) 2.0 V

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6. Ib = ?

a) 0.6 A

b) 0.5 A

c) 0.4 A

d) 0.3 A

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7. i1 = ?

a) 0.6 A

b) 2.1 A

c) 1.7 A

d) 1.1 A

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8. i1 = ?

a) 1 mA

b) 1.5 mA

c) 2 mA

d) 2.5 mA

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9. i1 = ?

a) 4 A

b) 3 A

c) 6 A

d) 5 A

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10. i1 = ?

a) 20 mA

b) 15 mA

c) 10 mA

d) 5 mA

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## Set 3

1. Which of the following is method to model a diode’s forward characteristics?

a) Iteration method

b) Graphical method

c) Constant-voltage drop model

d) All of the mentioned

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2. A voltage regulator needs to provide a constant voltage in spite of the fact that there may be

a) Change in the load current drawn from the terminals of the regulator

b) Change of the DC power supply that feeds the regulator circuit

c) None of the mentioned

d) All of the mentioned

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(Q.3-Q.4) For the circuit shown below calculate

3. Calculate the %age change in the regulated voltage caused by a change of ±10% in the input voltage. (R_{L} is not connected to the circuit)

a) ± 0.5%

b) ± 1%

c) ± 5%

d) ± 10%

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_{d}= 25mV/7.9mA at room temperature or 3.2Ω Total resistance of the diode connection = r = 9.6Ω The series combination of R and r acts as a voltage divider, hence ▲V

_{0}= ±r/r+R or 9.5 mA or ± 0.5%.

4. Calculate the change in the voltage when R_{L} is connected as shown

a) -10 mA

b) -15 mA

c) -20 mA

d) -25 mA

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_{L}is connected it draws approx. 2.1v/1000 A current or 2.1 mA. Hence the current in the diode decreases by approximately 2.1 mA. The voltage change across the diode is thus -2.1mA * 9.6 Ω or -20mA.

5. The value of the diode small-signal resistance r_{d} at bias currents of 0.1 mA is

a) 250 Ω

b) 25 Ω

c) 2.5 Ω

d) 0.25 Ω

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_{d}= 25mV/0.1mA or 250 Ω.

6. In many applications, a conducting diode is modeled as having a constant voltage drop, usually approximately

a) 1 V

b) 0.1 V

c) 0.7 V

d) 7V

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7. The graphical method of modeling a diode characteristics is based on

a) Iteration method

b) Constant voltage drop method

c) Small signal approximation

d) Exponential method

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8. For small-signal operation around the dc bias point, the diode is modeled by a resistance equal to the

a) Slope of the i-v characteristics of the diode at the bias point

b) Square root of the slope of the i-v characteristics of the diode at the bias point

c) Inverse of the slope of the i-v characteristics of the diode at the bias point

d) Square root of the inverse of the slope of the i-v characteristics of the diode at the bias point

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9. The other name for bias point is

a) Quiescent point

b) Node point

c) Terminal point

d) Static point

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10. In iteration method for modelling a diode the answer obtained by each subsequent iteration is

a) Is close to the true value

b) Is close to the value obtained by exponential method

c) All of the mentioned

d) None of the mentioned

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## Set 4

(Q.1 & Q.2) Various measurements are made on an NMOS amplifier for which the drain resistor R_{D} is 20 kΩ. First, DC measurements show the voltage across the drain resistor, V_{RD}, to be 2 V and the gate-to-source bias voltage to be 1.2 V. Then, ac measurements with small signals show the voltage gain to be −10 V/V.

1. What is the value of V_{t} for this transistor?

a) 0.7V

b) 0.8V

c) 0.9V

d) 1.0V

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2. If the process transconductance parameter is 50μA/V^{2}, what is the MOSFET’s W/L?

a) 25

b) 50

c) 75

d) 100

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(Q.3-Q.5) Consider the amplifier below for the case V_{DD} = 5 V, R_{D} = 24 kΩ, (W/L) = 1 mA/V^{2}, and V_{t} = 1 V.

3. If the amplifier is biased to operate with an overdrive voltage V_{OV} of 0.5 V, find the incremental gain at the bias point.

a) -3 V/V

b) -6 V/V

c) -9 V/V

d) -12 V/V

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4. For amplifier biased to operate with an overdrive voltage of 0.5V, and disregarding the distortion caused by the MOSFET’s square-law characteristic, what is the largest amplitude of a sine-wave voltage signal that can be applied at the input while the transistor remains in saturation?

a) 1.61 V

b) 1.5 V

c) 0.11 V

d) 3.11 V

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5. For the input signal of 1.5V what is the value of the gain value obtained?

a) -12.24 V/V

b) -12.44 V/V

c) -12.64 V/V

d) -12.84 V/V

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_{oq}– V

_{OB}= 2 – 0.61 = 1.39v. The gain implied by amplitude is Gain = -1.39/0.11 = -12.64 V/V.

6. Which of the following is the fastest switching device?

a) JEFT

b) Triode

c) MOSFET

d) BJT

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7. Bias point is also referred by the name

a) DC Operating Point

b) Quiescent Point

c) None of the mentioned

d) All of the mentioned

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(Q.8 –Q.10) Consider the amplifier circuit shown below. The transistor is specified to have V_{t} = 0.4 V, k_{n} = 0.4 mA/V2, W/L = 10 and λ = 0. Also, let V_{DD} = 1.8V, R_{D} = 17.5kΩ, V_{GS} = 0.6V and v_{gs} = 0V.

8. Find I_{D}.

a) 0.08 mA

b) 0.16 mA

c) 0.4 mA

d) 0.8 mA

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9. Find V_{DS}.

a) 0.1V

b) 0.2 V

c) 0.4 V

d) 0.8 V

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10. Find A_{v}.

a) -12 V/V

b) -14 V/V

c) -16 V/V

d) -18 V/V

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_{v}= – k

_{n}V

_{ov}R

_{D}= -0.4 * 10 * 0.2 * 17.5 = – 14.4v

## Set 5

1. If a MOSFET is to be used in the making of an amplifier then it must work in

a) Cut-off region

b) Triode region

c) Saturation region

d) Both cut-off and triode region can be used

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2. For MOSFET is to be used as a switch then it must operate in

a) Cut-off region

b) Triode region

c) Saturation region

d) Both cut-off and triode region can be used

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(Q.3 & Q.4) Using the circuit shown below,

3. Determine the conditions in which the MOSFET is operating in the triode region.

i. V_{GD} > V_{t} (Threshold voltage)

ii. V_{D}S > V_{OV}

iii. I_{D} ∝ (V_{OV} – 0.5V_{DS})V_{DS}

a) i, ii, and iii are correct

b) i and iii are correct

c) i and ii are correct

d) ii and iii are correct

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4. Determine the conditions in which the MOSFET is operating in the saturation region

i. V_{GD} > V_{t} (Threshold voltage)

ii. V_{DS} > V_{OV}

iii. I_{D} ∝ (V_{OV})^{2}

a) i, ii, and iii are correct

b) i and iii are correct

c) i and ii are correct

d) ii and iii are correct

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5. In the saturation region of the MOSFET the saturation current is

a) Independent of the voltage difference between the source and the drain

b) Depends directly on the voltage difference between the source and the drain

c) Depends directly on the overdriving voltage

d) Depends directly on the voltage supplied to the gate terminal

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6. An n-channel MOSFET operating with V_{OV}=0.5V exhibits a linear resistance = 1 kΩ when V_{DS} is very small. What is the value of the device transconductance parameter k_{n}?

a) 2 mA/V^{2}

b) 20 mA/V^{2}

c) 0.2 A/V^{2}

d) 2 A/V^{2}

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_{n}.

7. An NMOS transistor is operating at the edge of saturation with an overdrive voltage V_{OV} and a drain current I_{D}. If is V_{OV} is doubled, and we must maintain operation at the edge of saturation, what value of drain current results?

a) 0.25I_{D}

b) 0.5I_{D}

c) 2I_{D}

d) 4I_{D}

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_{0}is directly proportional to V

_{OS}.

(Q.8-Q.10) Using the circuit below answer the question

8. Which of the following is true for the triode region?

a. V_{DG} > V_{tp}

b. V_{SD} < V_{OV}

c. I_{D} ∝ V_{OV}

d. None of the mentioned

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_{DG}> |V

_{tp}| and V

_{SD}< |V

_{OV}|.

9. Which of the following is true for the saturation region?

a) V_{DG} ≤ |V_{tp}|

b) V_{SD} ≤| V_{OV}|

c) V_{DG} < |V_{tp}|

d) V_{SD} <| V_{OV}|

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10. The current i_{D}

a) Depends linearly on V_{OV} in the saturation region

b) Depends on the square of V_{OV} in the saturation region

c) Depends inversely on V_{OV} in the triode region

d) None of the mentioned

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_{0}in different regions.