# Multiple choice question for engineering

## Set 1

1. The network function (s^{2} + 4s)/(s + 1)(s + 2)(s + 3) represents

a) RC impedance

b) RL impedance

c) LC impedance

d) None of the mentioned

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2. The network function (3s^{2} + 8s)/(s + 1)(s + 3) represents

a) RC impedance

b) RL impedance

c) LC impedance

d) None of the mentioned

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3. The network function (s + 1)(s + 4)/s(s + 2)(s + 5) represents

a) RC impedance

b) RL impedance

c) LC impedance

d) All of the mentioned

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4. The network function s^2 + 10s + 24/s^{2} + 8s + 15 represents

a) RC impedance

b) RL impedance

c) LC impedance

d) None of the mentioned

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5. A valid immittance function is

a) (s + 4)(s + 8)/(s + 2)(s – 5)

b) s(s + 1)/(s + 2)(s + 5)

c) s(s + 2)(s + 3)/(s + 1)(s + 4)

d) s(s + 2)(s + 6)/(s + 1)(s + 4)

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6. The network function (s^{2} + 8s +15)/(s^{2} + 6s + 8) is

a) RL admittance

b) RC admittance

c) LC admittance

d) All of the mentioned

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7. The voltage response of a network to a unit step input is Vo(s) = 10/s(s^{2} + 8s + 16). The response is

a) under damped

b) over damped

c) critically damped

d) can’t be determined

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8. The current response of a network to a unit step input is Io(s) = 10(s + 2)/s(s^{2} + 11s + 30). The response is

a) Under damped

b) Over damped

c) Critically damped

d) None of the mentioned

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Circuit for q.9-Q.10

9. The ratio of the transfer function Io/Is is

a) s(s + 4)/(s^{2} + 3s + 4)

b) s(s + 4)/(s + 1)(s + 3)

c) (s^{2} + 3s + 4)/s(s + 4)

d) (s + 1)(s + 3)/s(s + 4)

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10. The response is

a) Over damped

b) Under damped

c) Critically damped

d) can’t be determined

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## Set 2

1. Buffer amplifier needs to have

a) Low input resistance and low output resistance

b) High Input resistance and high output resistance

c) Low input resistance and high output resistance

d) High input resistance and low output resistance

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2. The ideal values for the input resistance (Ri) and the output resistance (Ro) of a transconductance amplifier are

a) R_{i} = 0 and R_{o} = 0

b) R_{i} = ∞ and R_{0} = ∞

c) R_{i} = 0 and R_{0} = ∞

d) R_{i} = ∞ and R_{i} = 0

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3. An amplifier has a voltage gain of 40db. The value of A_{VO} is

a) 10

b) 100

c) 20

d) 200

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_{VO}= 40. Solving for A

_{vo}gives 100 as the answer.

4. The output voltage of a voltage amplifier has been found to decrease by 20% when a load resistance of 1 kΩ is connected. What is the value of the amplifier output resistance?

a) 50Ω

b) 200Ω

c) 250Ω

d) 350Ω

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5. Which of the following is a transresistance amplifier?

a)

b)

c)

d)

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6. The signal to be amplified is current signal and the output desired is a voltage signal. Which of the following amplifier can perform this task?

a) Voltage amplifier

b) Current amplifier

c) Transconductance amplifier

d) Transresistance amplifier

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7. You are given two amplifiers, A and B, to connect in cascade between a 10-mV, 100-kΩ source (S) and a 100-Ω load (L). The amplifiers have voltage gain, input resistance, and output resistance as follows: for A, 100 V/V, 10 kΩ, 10 kΩ, respectively; for B, 1 V/V, 100 kΩ, 100 Ω, respectively. Your problem is to decide how the amplifiers should be connected so that the voltage gain is maximum.

a) SABL

b) SBAL

c) Both have the same voltage gain

d) None as neither combination is able to amplify the input signal

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8. A transconductance amplifier with Ri = 2 kΩ, Gm = 40 mA/V, and Ro = 20 kΩ is fed with a voltage source having a source resistance of 2 kΩ and is loaded with a 1-kΩ resistance. Find the voltage gain realized.

a) 18.05 V/V

b) 19.05 V/V

c) 20.05 V/V

d) 21.05V/V

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9. The ratio of the short circuit current gain of a current amplifier (A_{i}) to the open circuit voltage gain of a voltage amplifier (A_{V}), given that both amplifiers have the same value of the input resistance (R_{i}) and output resistance (R_{0}), is

a) R_{i}

b) R_{o}

c) R_{i} / R_{0}

d) R_{o} / R_{i}

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10. The ratio of the open circuit voltage of a voltage amplifier (A_{V}) to the short circuit transconductance of a (G_{m}) of a transconductance amplifier, given that both have the same value of the internal resistance (R_{i}) and the output resistance (R_{0}), is

a) R_{i}

b) R_{0}

c) 1/R_{i}

d) 1/R_{0}

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## Set 3

1. What is the number of capacitors and inductors used in a CLC filter?

a) 1, 2 respectively

b) 2, 1 respectively

c) 1, 1 respectively

d) 2, 2 respectively

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2. Major part of the filtering is done by the first capacitor in a CLC filter because _________

a) The capacitor offers a very low reactance to the ripple frequency

b) The capacitor offers a very high reactance to the ripple frequency

c) The inductor offers a very low reactance to the ripple frequency

d) The inductor offers a very high reactance to the ripple frequency

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3. At f=50Hz, the ripple factor of CLC filter is_________

a) ϒ=5700RL / (LC_{1}C_{2})

b) ϒ=5700/ (LC_{1}C_{2}R_{L})

c) ϒ=5700LC_{1}/ (C_{2}R_{L})

d) ϒ=5700C_{1}C_{2}/ (LR_{L})

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_{1}C

_{2}R

_{L}) at 50Hz.

4. A single phase full wave rectifier makes use of pi section filter with 10µF capacitors and a choke of 10henry. The secondary voltage is 280V and the load current is 100mA. Determine the dc output voltage when f=50Hz.

a) 345V

b) 521V

c) 243V

d) 346V

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_{RMS}=280V So, V¬m = 1.414*280=396V. From theory of capacitor filter, V

_{DC}= V

_{m}–I

_{DC}/4fC=396-0.1/ (4*50*10*10

^{-6})=346V.

5. For a given CLC filter, the operating frequency is 50Hz and 10µF capacitors used. The load resistance is 3460Ω with an inductance of 10henry. Calculate the ripple factor.

a) 0.165%

b) 0.142%

c) 0.178%

d) 0.321%

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_{1}C

_{2}R

_{L}) =5700 / (10*100*10

^{-12}*3460) =0.165%.

6. The inductor is placed in the L section filter because_________

a) It offers zero resistance to DC component

b) It offers infinite resistance to DC component

c) It bypasses the DC component

d) It bypasses the AC component

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7. The voltage in case of a full wave rectifier in a CLC filter is_________

a) V_{ϒ} = I_{DC}/2fC

b) V_{ϒ} = I_{DC} fC

c) V_{ϒ} = I_{DC}/fC

d) V_{ϒ} = 2I_{DC}fC

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_{PEAK}.

8. The advantages of a pi-filter is_________

a) low output voltage

b) low PIV

c) low ripple factor

d) high voltage regulation

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9. What is the relation between time constant and load resistance?

a) They don’t depend on each other

b) They are directly proportional

c) They are inversely proportional

d) Cannot be predicted

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10. The output waveform of CLC filter is superimposed by a waveform referred to as_________

a) Square wave

b) Triangular wave

c) Saw tooth wave

d) Sine wave

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## Set 4

1. What is the SI unit of conductivity?

a) Ωm

b) (Ωm)-1

c) Ω

d) m

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2. Which of the following expressions doesn’t represent the correct formula for Drift current density?

a) J=σE

b) J=qnµE

c) J=µE

d) None

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3. Does a semiconductor satisfy the ohm’s law?

a) True

b) False

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4. In which range of temperature, freeze out point begins to occur?

a) Higher range

b) Lower range

c) Middle range

d) None

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5. Which of the following expression represents the correct formula for the conductivity in an intrinsic material?

a) ρ=e(μ_{n+μp })ni

b) σ=e(μ_{n+μp })ni

c) σ=1/(e(μ_{n+μp })ni)

d) ρ=1/(e(μ_{n+μp })ni)

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6. What is the voltage difference if the current is 1mA and length and area is 2cm and 4cm2 respectively?(ρ=2Ωm)

a) 0.025V

b) 25V

c) 0.25V

d) None

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7. Is resistivity is a function of temperature?

a)True

b)False

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8. What is the electric field when the voltage applied is 5V and the length is 100cm?

a) 0.5V/m

b) 5V/m

c) 50V/m

d) None

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9. Calculate the average random thermal energy at T=300K?

a) 0.038eV

b) 3.8eV

c) 38eV

d) 0.38eV

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10.

In the above figure, a semiconductor having an area ‘A’ and length ‘L’ and carrying current ‘I’ applied a voltage of ‘V’ volts across it. Calculate the relation between V and A?

a) V= ((ρ*L)/A)*I

b) V= ((ρ*A)/L)*I

c) V= ((ρ*I)/(A*L))

d) V=((ρ*I*A*L)

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## Set 5

(Q.1-Q.2) The number of cars arriving at ICICI bank drive-in window during 10-min period is Poisson random variable X with b=2.

1. The probability that more than 3 cars will arrive during any 10 min period is

a) 0.249

b) 0.143

c) 0.346

d) 0.543

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2. The probability that no car will arrive is

a) 0.516

b) 0.459

c) 0.246

d) 0.135

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(Q.3-Q.5) Delhi averages three murder per week and their occurrences follow a Poisson distribution.

3. The probability that there will be five or more murder in a given week is

a) 0.1847

b) 0.2461

c) 0.3927

d) 0.4167

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4. On the average, how many weeks a year can Delhi expect to have no murders ?

a) 1.4

b) 1.9

c) 2.6

d) 3.4

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5. How many weeds per year (average) can the Delhi expect the number of murders per week to equal or exceed the average number per week?

a) 15

b) 20

c) 25

d) 30

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(Q.6-Q.8) The random variable X is defined by the density f(x) = 0.5u(x) e^{(0.5x)}

6. The expect value of g(x) = X^{3} is

a) 48

b) 192

c) 36

d) 72

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^{3}].

7. The mean of the random variable x is

a) 1/4

b) 1/6

c) 1/3

d) 1/5

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8. The variance of the random variable x is

a) 1/10

b) 3/80

c) 5/16

d) 3/16

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^{2}30] – 1/16.

(Q.9-Q.10) A joint sample space for two random variable X and Y has four elements (1,1), (2,2), (3,3) and (4,4). Probabilities of these elements are 0.1, 0.35, 0.05 and 0.5 respectively.

9. The probability of the event{X 2.5, Y 6} is

a) 0.45

b) 0.50

c) 0.55

d) 0.60

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10. The probability of the event that X is less than three is

a) 0.45

b) 0.50

c) 0.55

d) 0.60