# Multiple choice question for engineering

## Set 1

1. Op-amp was introduced by __________

a) Fairchild

b) Maxwell

c) Rutherford

d) Sahani

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2. The number of terminals in an Op-amp ______________

a) 6

b) 2

c) 5

d) 3

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3. The Op-amp is a type of ___________

a) Differential amplifier

b) Integrated amplifier

c) Isolation amplifier

d) Feedback amplifier

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4. In the circuit of Op-amp given V- stands for _________

a) Non-inverting input

b) Non-inverting output

c) Inverting input

d) Inverting output

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5. When the input voltage difference is small in magnitude, the Op-amp behaves as ____________

a) Non-linear device

b) Linear device

c) Complex device

d) Bipolar device

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6. If the output voltage is not a linear function of input voltage then ____________

a) Op-amp acts a linear device

b) Op-amp acts as a non-linear device

c) Op-amp acts a polar device

d) Op-amp acts as an inverter

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7. The negative feedback causes the input voltage difference to ____________

a.) 1

b) Increase

c) Decrease

d) 0

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8. Find the gain for the following circuit.

a) -2

b) 2

c) -1

d) 1

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_{out}/V

_{in}= -R

_{2}/R

_{1}.

9. Calculate the gain for the Op-amp given.

a) 0.719

b) 2.572

c) 1.390

d) 1.237

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_{out}/V

_{in}= -R

_{2}/R

_{1}= -5.98*10

^{-3}/4.3*10

^{-3}.

10. Given Op-amp is ideal. Calculate v_{o} if v_{a}=1v and v_{b}=0v.

a) -4v

b) -2.5v

c) 4v

d) 2.5v

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_{p}=v

_{b}=0 and v

_{n}=v

_{p}). Node-voltage equation is i

_{50}=i

_{125}=i

_{0}. i

_{50}= (v

_{a}-v

_{n})/50 =1/50 mA. I

_{125}= (v

_{0}-v

_{n})/125 = v

_{0}/125 mA. 1/50 + v

_{0}/125 = 0. v

_{0}is -2.5volts.

## Set 2

1) The symbol used for representing Independent sources

a) Diamond

b) Square

c) Circle

d) Triangle

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2. Controlled sources are also known as

a) Independent sources

b) Dependent sources

c) Ideal sources

d) Voltage sources

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3.

I_{3} = α v_{x} .This is

a) Voltage control voltage source

b) Current control voltage source

c) Voltage control current source

d) Current control current source

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_{3}=αv

_{x}means ix value depends on v

_{x}Controlled voltage is v

_{x}.

4. Inductor is _______________ element.

a) Active

b) Passive

c) Linear

d) Polar

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5.

Which of the above is valid?

a) 1

b) 2

c) Both

d) Neither 1 nor 2

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6.

The above circuit is valid.

a) False

b) True

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7. The opposing capacity of materials against the current flow is

a) Conductance

b) Inductance

c) Susceptance

d) Resistance

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8. The conductance of a 923Ω resistance is

a) 1.08 * 10^{-3} mho

b) 1.08 * 10^{-4} mho

c) 1.02 * 10^{-3} mho

d) 1.02 * 10^{-4} mho

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^{-3}mho

9. The current passing through a circuit is 7.2A and the power at the terminals is 27 watts.

Existence is ___________ ohms.

a) 0.5402

b) 0.5208

c) 0.5972

d) 0.5792

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^{2}R R = P/i

^{2}=27/ (7.2)

^{2}= 0.5208Ω.

10. Relation between power, voltage and conductance

a) V = P^{2}.G

b) V = P^{2}/G

c) P = v^{2}/G

d) P = V^{2} G

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^{2}/R = v

^{2}G.

## Set 3

1. Which among the following chemical bond were described by Kossel and Lewis?

a) Metallic bond

b) Polar covalent bond

c) Coordinate bond

d) Ionic and Covalent bond

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2. Which among the following is not a property of Ionic bond?

a) Losing of electrons

b) Gain of electrons

c) Sharing of electrons

d) Transfer of electrons

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3. Which among the following formation is not an example of Covalent bond?

a) LiF

b) NH_{3}

c) CF_{4}

d) HF

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4. State whether the given statement is true or false “Ionic bonds are non-directional”

a) True

b) False

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5. If a bond is made up of a large number of organic compound, then the bond is termed as?

a) Ionic bond

b) Metallic bond

c) Covalent bond

d) Dipolar bond

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6. Which among the following is not an example of hydrogen bond?

a) H_{2}0

b) Liquid HCl

c) NH_{3}

d) CHCl_{3}

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7. Atoms undergo bonding in order to ?

a) Attain stability

b) Lose stability

c) Move freely

d) increase energy

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8. An atom differs from its ion in which among the following ?

a) Mass number

b) Atomic number

c) Neutrons

d) Number of protons

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9. Which among the following is both a molecule and a compound?

a) C_{6} H_{12} O_{6}

b) H_{2}O

c) CO_{2}

d) NaCl

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_{2}O is both a molecule and a compound. This is because the atoms which make them are not the same.

10. Bond energy and the corresponding bond length vary directly with each other. comment whether the statement is true or false.

a) True

b) False

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## Set 4

1. A single phase full bridge inverter has RLC load with R = 4 Ω, Xl = 11 Ω and Xc = 20.54 Ω. The dc input voltage is 230 V. Find the value of fundamental load power.

a) 1633 W

b) 1603 W

c) 1576 W

d) none of the mentioned

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^{2}+ (Xl – Xc)

^{2}]

^{1/2}I = V/Z = 28.31 I(rms)(fundamental) = V/Z√2 = (292.85)/(1.414 x 10.345) = 20.02 A Fundamental Load power = (20.02)

^{2}x R = (20.02)

^{2}x 4 = 1603.2 Watts.

2. A single phase full bridge inverter has RLC load with R = 4 Ω, L = 35 mH and C = 155 μF. The dc input voltage is 230 V and the output frequency is 50 Hz. Find the angle by which the third harmonic current will lead/lag the third harmonic output voltage.

a) 67.25°

b) 96.4°

c) 49.87°

d) 81.3°

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_{L}= 2 x 3.14 x 50 x 0.035 = 10.99 Ω X

_{C}= 1/(2 x 3.14 x 50 x 155 x 10

^{-6}) = 20.54 Ω For the third harmonic component X

_{L}(3rd harmonic) = 10.99 x 3 = 33 Ω (approx.) X

_{C}(3rd harmonic) = 20.54/3 = 6.846 Ω R = 4 Ω P = tan

^{-1}(X

_{L}– X

_{C})/R = 81.3°.

3. A single phase half bridge inverter has RLC load. The dc input voltage (Vs/2) = 115 V and the output frequency is 50 Hz. The expression for the load voltage up to the fifth harmonic will be given by

a) 146 sin 314t + 48.81 sin 314t + 58.57 sin 318t + 28.31 sin 318t + 3.686 sin 318t

b) 146 sin 314t + 48.81 sin (3 x 314t) + 29.28 sin (5 x 318t)

c) 146 sin 314t + 48.81 sin (2 x 314t) + 58.57 sin (3 x 318t)

d) none of the mentioned

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4. Let Vs be the amplitude of the output voltage and P be the output power for a single-phase half bridge inverter. Then the corresponding values for a full bridge inverter would be

a) 2Vs, 4P

b) 2Vs, 2P

c) Vs, P

d) 2Vs, P

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5. In VSI (voltage source inverters)

a) both voltage and current depend on the load impedance

b) only voltage depends on the load impedance

c) only current depends on the load impedance

d) none of the mentioned

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6. The harmonic factor of nth harmonic is given by

a) V_{n}

b) V_{1}/V_{n}

c) V_{n}/V_{1}

d) None of the mentioned

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_{1}).

7. ____________ is the measure of the contribution of any individual harmonic to the inverter output voltage.

a) THD

b) Distortion Factor

c) Harmonic Factor

d) TUF

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8. The Total Harmonic Distortion (THD) is the ratio of

a) rms value of all the harmonic components to the rms value of the fundamental component

b) average value of all the harmonic components to the rms value of the fundamental component

c) rms value of all the third harmonic component to the rms value of the fundamental component

d) rms value of all the fundamental component to the rms value of all the harmonic components

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_{1}V

_{1}= Fundamental component Vo = value of all the harmonic components expect the fundamental.

9. The HF (Harmonic factor of nth harmonic) is the ratio of

a) an average and a rms value

b) a rms and an average value

c) two volt-ampere values

d) two rms values

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10. The total harmonic distortion (THD) is the measure of

a) input vs output power factor

b) temperature sensitivity

c) waveform distortion

d) contribution of each harmonic to the total output

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## Set 5

1. For a certain SCR configuration, the below shown waveform is obtained. Find the value of the average output voltage with α = 30° & Vs = 240 V.

a) 50.27 V

b) 100.8 V

c) 140 V

d) 120 V

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_{avg}= ∫ Vm Sin ωt d(ωt) where the integration runs from α to π V

_{avg}= Vm/2π (1+cos α).

2. A single-phase half wave circuit has Vs = 230 V with a R load of 100 Ω. Find the average load current at α = 30°.

a) 1.45 A

b) 0.57 A

c) 0.96 A

d) 2.3 A

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3. A single phase 230 V, 1 kW heater is connected across a 1-phase 230 V, 50 Hz supply through an SCR. The firing angle of the SCR is adjusted to give a rms voltage of 155 V. Find the power absorbed by the heater element.

a) 250 watts

b) 1 kW

c) 454 watts

d) 378 watts

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^{2}/1kW = 52.9 Ω Now, P = Vrms

^{2}/R = 155

^{2}/52.9.

4. For a single phase half-wave thyristor circuit with R load, the power delivered to the resistive load is

a) (average load voltage) x (average load current)

b) (rms supply voltage)^{2}/R

c) (rms load voltage)^{2}/R

d) (average load voltage)/R

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^{2}.R V = IR I = V/R Hence, P = V

^{2}/R.

5. For a single phase half-wave thyristor circuit with R load, the input power factor is given by

a) rms source voltage/total rms line current

b) rms input power/power delivered to the load

c) cos α

d) power delivered to load/input VA

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6. For the below shown circuit,

The load voltage waveform from ωt = π to ωt = π+α = β (extinction angle) is

a) gradually rising

b) going from positive to negative

c) gradually decaying

d) zero

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7.For the below shown circuit,

The SCR is gated at α. At ωt = π

a) load voltage & load current are both zero

b) only load voltage is zero

c) only load current is zero

d) both are non zero & non negative

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8. In case of a single-phase half-wave circuit with RL load, with firing angle α and extinction angle β, the conduction angle γ can be written as

a) γ = β+α

b) γ = β-α

c) γ = β/α

d) γ = α/β

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9. For a half-wave single phase thyristor rectifier circuit with any type of load the _______ + _________ waves must ideally give the supply voltage waveform.

a) load voltage, load current

b) load voltage, thyristor voltage

c) supply current, load voltage

d) supply current, thyristor voltage

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10. In case of a single-phase half-wave circuit with RL load, with firing angle α and extinction angle β, the thyristor is reversed biased from

a) β to α

b) β to 2π+α

c) β to 2π

d) β to 2β