# Multiple choice question for engineering

## Set 1

1. What is the coupling coefficient when all the flux of coil 1 links with coil 2?

a) 0

b) 100

c) 1

d) Insufficient information provided

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2. What is the coupling coefficient when there is ideal coupling?

a) 0

b) 100

c) 1

d) Insufficient information provided

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3. Can the coupling coefficient practically ever be equal to 1?

a) Yes

b) No

c) Depends on current in coil 1

d) Depends on current in coil 2

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4. Mutual inductance between to coupled coils depends on?

a) Amount of flux linkage

b) Rate of change of flux linkage

c) Rate of change of current

d) Flux density

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5. Which, among the following, is the correct formula to fing coupling coefficient?

a) k=M/sqrt(L1L2)

b) k=M/sqrt(L1^{2})

c) k=M/sqrt(L2^{2})

d) k=M/(L1L2)

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6. What happens to coupling coefficient when the flux linkage of coil 1 and coil 2 increases?

a) Increases

b) Decreases

c) Remains the same

d) Becomes zero

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7. What is the SI unit of coupling coefficient?

a) H

b) H^{-1}

c) No unit

d) H^{2}

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8. Find the coupling coefficient if the Mutual inductance is 20H, the inductance of coil 1 is 2H and the inductance of coil 2 is 8H.

a) 5

b) 20

c) 2

d) 8

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9. Find the value of x if the Mutual inductance is x H, the inductance of coil 1 is 2H and the inductance of coil 2 is 8H. The coupling coefficient is 5.

a) 10H

b) 20H

c) 16H

d) 15H

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10. Find the value of x if the Mutual inductance is 20H, the inductance of coil 1 is xH and the inductance of coil 2 is 8H. The coupling coefficient is 5.

a) 2H

b) 4H

c) 6H

d) 8H

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## Set 2

1. In a series RLC circuit, the phase difference between the current in the capacitor and the current in the resistor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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2. In a series RLC circuit, the phase difference between the current in the inductor and the current in the resistor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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3. In a series RLC circuit, the phase difference between the current in the capacitor and the current in the inductor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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4. In a series RLC circuit, the phase difference between the current in the circuit and the voltage across the resistor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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5. In a series RLC circuit, the phase difference between the current in the circuit and the voltage across the capacitor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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6. In a series RLC circuit, the phase difference between the current in the circuit and the voltage across the resistor is?

a) 0 degrees

b) 90 degrees

c) 180 degrees

d) 360 degrees

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7. _________ the resonant frequency, the current in the inductor lags the voltage in a series RLC circuit.

a) Above

b) Below

c) Equal to

d) Depends on the circuit

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8. _________ the resonant frequency, the current in the capacitor leads the voltage in a series RLC circuit.

a) Above

b) Below

c) Equal to

d) Depends on the circuit

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9. The current in the inductor ___________ the voltage in a series RLC circuit above the resonant frequency.

a) Leads

b) Lags

c) Equal to

d) Depends on the circuit

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10. The current in the capacitor ___________ the voltage in a series RLC circuit below the resonant frequency.

a) Leads

b) Lags

c) Equal to

d) Depends on the circuit

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## Set 3

1. The value of the 3 resistances when connected in star connection is_________

a) 2.32ohm,1.22ohm, 4.54ohm

b) 3.55ohm, 4.33ohm, 5.67ohm

c) 2.78ohm, 1.67ohm, 0.83ohm

d) 4.53ohm, 6.66ohm, 1.23ohm

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2. Which, among the following is the right expression for converting from delta to star?

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

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

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

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

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3. Find the equivalent star network.

a) 2.3ohm, 2.3ohm, 2.3ohm

b) 1.2ohm, 1.2ohm, 1.2ohm

c) 3.3ohm, 3.3ohm, 3.3ohm

d) 4.5ohm, 4.5ohm, 4.5ohm

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4. Star 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 delta connection. After transforming to star, the resistance at A will be?

a) Rab*Rac/(Rab+Rbc+Rca)

b) Rab/(Rab+Rbc+Rca)

c) Rbc*Rac/(Rab+Rbc+Rca)

d) Rac/(Rab+Rbc+Rca)

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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 delta connection. After transforming to star, the resistance at B will be?

a) Rac/(Rab+Rbc+Rca)

b) Rab/(Rab+Rbc+Rca)

c) Rbc*Rab/(Rab+Rbc+Rca)

d) Rab/(Rab+Rbc+Rca)

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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 delta connection. After transforming to star, the resistance at C will be?

a) Rac/(Rab+Rbc+Rca)

b) Rab/(Rab+Rbc+Rca)

c) Rbc*Rac/(Rab+Rbc+Rca)

d) Rab/(Rab+Rbc+Rca)

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8. Find the current in the circuit.

a) 0.54A

b) 0.65A

c) 0.67A

d) 0.87A

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9. If a 6 ohm, 2ohm and 4ohm resistor is connected in delta, find the equivalent star connection.

a) 1ohm, 2ohm, 3ohm

b) 2ohm, 4ohm, 7ohm

c) 5ohm, 4ohm, 2ohm

d) 1ohm, 2ohm, 32/3ohm

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10. If a 4ohm, 3ohm and 2ohm resistor is connected in delta, find the equivalent star connection.

a) 8/9ohm, 4/3ohm, 2/3ohm

b) 8/9ohm, 4/3ohm, 7/3ohm

c) 7/9ohm, 4/3ohm, 2/3ohm

d) 8/9ohm, 5/3ohm, 2/3ohm

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## Set 4

1. The unit for dielectric strength is ____________

a) V/m^{2}

b) MV/m^{2}

c) MV/m

d) Vm

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2. If the Voltage increases, what happens to dielectric strength?

a) Increases

b) Decreases

c) Remains the same

d) Becomes zero

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3. The electric fields of dielectrics having the same cross sectional area in series is related to their relative permittivities in which way?

a) Directly proportional

b) Inversely proportional

c) Equal

d) Not related

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4. If the potential difference in a material is 4MV and the thickness of the material is 2m, calculate the dielectric strength.

a) 2MV/m

b) 4MV/m

c) 6MV/m

d) 8MV/m

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5. If the dielectric strength of a material is 4MV/m and its potential difference is 28MV, calculate the thickness of the material.

a) 4m

b) 7m

c) 5m

d) 11m

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6. If the thickness of the material increases, what happens to the dielectric strength?

a) Increases

b) Decreases

c) Remains the same

d) Becomes zero

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7. The thickness of a material having dielectric strength 10MV/m is 5m, calculate the potential difference.

a) 2MV

b) 10MV

c) 50MV

d) 100MV

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8. What happens to the potential drop between the two plates of a capacitor when a dielectric is introduced between the plates?

a) Increases

b) Decreases

c) Remains the same

d) Becomes zero

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9. A dielectric is basically a ____________

a) Capacitor

b) Conductor

c) Insulator

d) Semiconductor

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10. What happens to the potential difference between the plates of a capacitor as the thickness of the dielectric slab increases?

a) Increases

b) Decreases

c) Remains the same

d) Becomes zero

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## Set 5

1. According to Faraday’s laws of electromagnetic inductance, an emf is induced in a conductor whenever?

a) The conductor is perpendicular to the magnetic field

b) Lies in the magnetic field

c) Cuts magnetic lines of flux

d) Moves parallel to the magnetic field

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2. Direction of induced emf is determined by __________

a) Fleming’s left hand rule

b) Fleming’s right hand rule

c) Faraday’s law

d) Right hand thumb rule

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3. “The direction of an induced e.m.f. is always such that it tends to set up a current opposing the motion or the change of flux responsible for inducing that e.m.f.”, this is the statement for?

a) Fleming’s left hand rule

b) Fleming’s right hand rule

c) Faraday’s law

d) Lenz’s law

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4. According to Fleming’s right hand rule, the thumb points towards?

a) Current

b) E.M.F.

c) Motion of the conductor

d) Magnetic flux

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5. According to Fleming’s right hand rule, the index finger points towards?

a) Current

b) E.M.F.

c) Motion of the conductor

d) Magnetic flux

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6. According to Fleming’s right hand rule, the middle finger points towards?

a) Current

b) E.M.F.

c) Motion of the conductor

d) Magnetic flux

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7. The relation between direction of induced emf and direction of motion of the conductor is?

a) Parallel

b) Equal

c) Not related

d) Perpendicular

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8. The relation between direction of induced emf and direction of magnetic flux is _______

a) Parallel

b) Equal

c) Not related

d) Perpendicular

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9. The relation between direction of magnetic flux and direction of motion of the conductor is _______

a) Parallel

b) Equal

c) Not related

d) Perpendicular

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10. North pole induces __________

a) Clockwise current

b) Anti-clockwise current

c) Zero current

d) Infinite current