# Multiple choice question for engineering

## Set 1

1. Find the equivalent delta circuit.

a) 3ohm, 10ohm, 5ohm

b) 3ohm, 10ohm, 15ohm

c) 3ohm, 1ohm, 5ohm

d) 3ohm, 10ohm, 6ohm

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2. Which, among the following is the correct expression for star-delta conversion?

a) R1=Ra*Rb/(Ra+Rb+Rc), R2=Rb*Rc/(Ra+Rb+Rc), R3=Rc*Ra/(Ra+Rb+Rc)b)

b) R1=Ra/(Ra+Rb+Rc), R2=Rb/(Ra+Rb+Rc), Rc=/(Ra+Rb+Rc)

c) R1=Ra+Rb+Ra*Rb/Rc, R2=Rc+Rb+Rc*Rb/Ra, R3=Ra+Rc+Ra*Rc/Rb

d) R1=Ra*Rb/Rc, R2=Rc*Rb/Ra, R3=Ra*Rc/Rb

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3. Find the equivalent resistance between X and Y.

a) 3.33 ohm

b) 4.34 ohm

c) 5.65 ohm

d) 2.38 ohm

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4. Delta connection is also known as____________

a) Y-connection

b) Mesh connection

c) Either Y-connection or mesh connection

d) Neither Y-connection nor mesh connection

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5. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in star connection. After transforming to delta, the resistance at A will be?

a) Rc+Rb+Rc*Rb/Ra

b) Rc+Rb+Ra*Rb/Rc

c) Ra+Rb+Ra*Rc/Rb

d) Rc+Rb+Rc*Ra/Rb

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6. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in star connection. After transforming to delta, the resistance at B will be?

a) Ra+Rb+Ra*Rb/Rc

b) Ra+Rc+Ra*Rc/Rb

c) Ra+Rb+Ra*Rc/Ra

d) Ra+Rc+Ra*Rb/Rc

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7. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in star connection. After transforming to delta, the resistance at C will be?

a) Rc+Rb+Ra*Rb/Rc

b) Ra+Rb+Ra*Rc/Rb

c) Ra+Rb+Ra*Rb/Rc

d) Ra+Rc+Ra*Rc/Rb

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8. If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection.

a) 1ohm, 3ohm, 2ohm

b) 4ohm, 3ohm, 5ohm

c) 4ohm, 5ohm, 2ohm

d) 5ohm, 3ohm, 2ohm

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9. If a 8/9ohm, 4/3ohm and 2/3ohm resistor is connected in star, find its delta equivalent.

a) 4ohm, 3ohm, 2ohm

b) 1ohm, 3ohm, 2ohm

c) 4ohm, 1ohm, 2ohm

d) 4ohm, 3ohm, 1ohm

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10. Find the equivalent resistance between A and B.

a) 32ohm

b) 31ohm

c) 30ohm

d) 29ohm

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## Set 2

1. In superposition theorem, when we consider the effect of one voltage source, all the other voltage sources are____________

a) Shorted

b) Opened

c) Removed

d) Undisturbed

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2. In superposition theorem, when we consider the effect of one current source, all the other voltage sources are____________

a) Shorted

b) Opened

c) Removed

d) Undisturbed

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3. In superposition theorem, when we consider the effect of one voltage source, all the other current sources are____________

a) Shorted

b) Opened

c) Removed

d) Undisturbed

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4. In superposition theorem, when we consider the effect of one current source, all the other current sources are____________

a) Shorted

b) Opened

c) Removed

d) Undisturbed

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5. Find the value of Vx due to the 16V source.

a) 4.2V

b) 3.2V

c) 2.3V

d) 6.3V

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6. Find Vx due to the 3A source.

a) 56V

b) 78V

c) 38V

d) 48V

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7. Find the value of Vx due to the 10V source.

a) 1V

b) 2V

c) 3V

d) 4V

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8. Find the voltage due to the 15A source.

a) 0V

b) 2V

c) 4V

d) 6V

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9. Superposition theorem is valid for_________

a) Linear systems

b) Non-linear systems

c) Both linear and non-linear systems

d) Neither linear nor non-linear systems

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10. Superposition theorem does not work for________

a) Current

b) Voltage

c) Power

d) Works for all: current, voltage and power

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## Set 3

1. Which, among the following, is the formula for induced emf?

a) e=d(phi)/dt

b) e=dt/d(phi)

c) e=t*phi

d) e=t^{2}phi

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2. The formula for induced emf is _______

a) emf=B^{2}l

b) emf=Bil

c) emf=Blv

d) emf=B^{2}v

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3. If a conductor 0.2m long moves with a velocity of 0.3m/s in a magnetic field of 5T, calculate the emf induced.

a) 0.3V

b) 0.03V

c) 30V

d) 3V

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4. Find the length of a conductor which is moving with a velocity 0.4m/s in a magnetic field of 8T, inducing an emf of 20V.

a) 50m

b) 5m

c) 6.25m

d) 0.5m

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5. Find the strength of magnetic field in a conductor 0.5m long moving with a velocity of 10m/s, inducing an emf of 20V.

a) 1T

b) 2T

c) 3T

d) 4T

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6. What is emf?

a) Force

b) Voltage

c) Current

d) Flux

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7. An E.M.F. can be induced by _________

a) Change in magnetic field

b) Change in the area of cross section

c) Change in angle between magnetic field and area

d) Change in magnetic field, area and angle

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8. The emf induced in a coil having N turns is?

a) e=phi/t

b) e=N*phi/t

c) e=N*phi*t

d) e=N^{2}*phi*t

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9. The total number of magnetic field lines passing through an area is termed as ________

a) Voltage

b) EMF

c) Magnetic flux

d) Magnetic flux density

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10. What is the consequence of motor effect?

a) Current

b) Voltage

c) Electromagnetic induction

d) EMF

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## Set 4

1. Calculate the Thevenin resistance across the terminal AB for the following circuit.

a) 4.34 ohm

b) 3.67 ohm

c) 3.43 ohm

d) 2.32 ohm

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2. Calculate Vth for the given circuit.

a) 5.54V

b) 3.33V

c) 6.67V

d) 3.67V

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3. Calculate the current across the 4 ohm resistor.

a) 0.86A

b) 1.23A

c) 2.22A

d) 0.67A

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4. The Thevenin voltage is the__________

a) Open circuit voltage

b) Short circuit voltage

c) Both open circuit and short circuit voltage

d) Neither open circuit nor short circuit voltage

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5. Thevenin resistance is found by ________

a) Shorting all voltage sources

b) Opening all current sources

c) Shorting all voltage sources and opening all current sources

d) Opening all voltage sources and shorting all current sources

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6. Thevenin’s theorem is true for __________

a) Linear networks

b) Non-Linear networks

c) Both linear networks and nonlinear networks

d) Neither linear networks nor non-linear networks

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7. In Thevenin’s theorem Vth is__________

a) Sum of two voltage sources

b) A single voltage source

c) Infinite voltage sources

d) 0

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8. Vth is found across the ____________ terminals of the network.

a) Input

b) Output

c) Neither input nor output

d) Either input or output

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9. Which of the following is also known as the dual of Thevenin’s theorem?

a) Norton’s theorem

b) Superposition theorem

c) Maximum power transfer theorem

d) Millman’s theorem

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10. Can we use Thevinin’s theorem on a circuit containing a BJT?

a) Yes

b) No

c) Depends on the BJT

d) Insufficient data provided

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## Set 5

1. A CR network is one which consists of _________

a) A capacitor and resistor connected in parallel

b) A capacitor and resistor connected in series

c) A network consisting of a capacitor only

d) A network consisting of a resistor only

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2. At DC, capacitor acts as _________

a) Open circuit

b) Short circuit

c) Resistor

d) Inductor

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3. In an RC series circuit, when the switch is closed and the circuit is complete, what is the response?

a) Response does not vary with time

b) Decays with time

c) Increases with time

d) First increases, then decreases

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4. If the switch is clocked at t=0, what is the current in the circuit?

a) 0A

b) 10A

c) 20A

d) Infinity

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5. Calculate the voltage across the capacitor at t=0.

a) 0A

b) 10A

c) 20A

d) Infinity

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6. Calculate di(0)/dt if the switch is closed at t=0.

a) -9.9A/s

b) -10A/s

c) 0A/s

d) -0.1A/s

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7. Calculate d^{2}i(0)/dt^{2} from the given circuit.

a) 10^{-6}A/s^{2}

b) 10^{-3}A/s^{2}

c) 10^{6}A/s^{2}

d) 10^{3}A/s^{2}

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^{2}i(0)/dt

^{2}+10di(0)/dt=0. Substituting the values of di/dt from the previous explanation, we get d

^{2}i(0)/dt

^{2}=10

^{-3}A/s

^{2}.

8. The current equation for the given circuit is?

a) i=10e^{(-0.01)}t A

b) i=10e^{(0.01)}t A

c) i=10e^{(-0.001)}t A

d) i=100e^{(-0.01)}t A

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^{(-0.01)}t A.

9. The expression for current in an RC circuit is?

a) i=(V/R)e^{(t/RC )}

b) i=(V/R)e^{(-t/RC )}

c) i=(V/R)/e^{(t/RC )}

d) i=(V/R)/e^{(-t/RC )}

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^{(-t/RC )}.

10. What is the voltage in the resistor as soon as the switch is closed at t=0.

a) 0V

b) Infinity

c) 220V

d) Insufficient information provided