Magnetism and Electromagnetism by Pavan

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Home Aptitude Logical Reasoning Verbal Ability GK Puzzles Engineering Interview Online TestElectrical Engineering :: Magnetism and Electromagnetism@ : Home > Electrical Engineering > Magnetism and Electromagnetism > General Questions

Exercise General Questions True or False"We cannot solve our problems with the same thinking we used when we created them."- Albert Einstein1.What is the reluctance of the circuit in problem 9 if the flux is 275 Wb?

A.0.0066 At/Wb

B.0.066 At/Wb

C.8,727 At/Wb

D.872 At/Wb

Answer & ExplanationAnswer: Option CExplanation:No answer description available for this question. Let us discuss. View Answer Workspace Report Discuss in Forum

2.When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage

A.increases

B.decreases

C.remains constant

D.reaches zero

Answer & ExplanationAnswer: Option AExplanation:No answer description available for this question. Let us discuss. View Answer Workspace Report Discuss in Forum

3.The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is

A.1,000 V

B.2,000 V

C.31.25 V

D.3,125 V

Answer & ExplanationAnswer: Option BExplanation:No answer description available for this question. Let us discuss. View Answer Workspace Report Discuss in Forum

4.For a given wirewound core, an increase in current through the coil

A.reverses the flux lines

B.decreases the flux density

C.increases the flux density

D.causes no change in flux density


5.If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density

A.increases

B.decreases

C.remains the same

D.doubles


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Exercise General Questions True or False"Hold a true friend with both hands."- (Proverb)6.When the current through the coil of an electromagnet reverses, the

A.direction of the magnetic field reverses

B.direction of the magnetic field remains unchanged

C.magnetic field expands

D.magnetic field collapses


7.What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and a permeability of 4,500 Wb/At m?

A.1111 At/Wb

B.111 At/Wb

C.11 At/Wb

D.1 At/Wb


8.A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will

A.increase

B.decrease

C.remain constant

D.be excessive


9.What is the flux density when the flux is 5.5 Wb and the cross-sectional area is 6 103 m2?

A.91.7 T

B.917 T

C.91 T

D.9.7 T


10.The unit for reluctance is

A.teslaB.At/Wb

C.At/mD.Wb


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Exercise General Questions True or False"Weakness of attitude becomes weakness of character."- Albert Einstein11.If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage

A.increases

B.decreases

C.is zero

D.will remain constant


12.There is 900 mA of current through a wire with 40 turns. What is the reluctance of the circuit if the flux is 400 Wb?

A.14,400 At/Wb

B.1,440 At/Wb

C.9,000 At/Wb

D.90,000 At/Wb

Answer & ExplanationAnswer: Option DExplanation:No answer description available for this question. Let us discuss. View Answer Workspace Report Discuss in Forum

13.A basic one-loop dc generator is rotated at 90 rev/s. How many times each second does the dc output voltage peak (reach maximum)?

A.90B.180

C.270D.360


14.What is the flux density in a magnetic field in which the flux in 0.1 m2 is 600 Wb?

A.6,000 T

B.600 T

C.600 T

D.6 T


15.The unit for permeability is

A.Wb/At m

B.At/m

C.At/Wb

D.Wb


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Exercise General Questions True or False"Everything you can imagine is real."- Pablo Picasso16.What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it?

A.18.75 At

B.30 At

C.300 At

D.187 At


17.The direction of a magnetic field within a magnet is

A.from south to north

B.from north to south

C.back to front

D.front to back


18.When the north poles of two bar magnets are brought close together, there will be

A.no force

B.a downward force

C.a force of attraction

D.a force of repulsion


19.The ability of a material to remain magnetized after removal of the magnetizing force is known as

A.permeabilityB.reluctance

C.hysteresisD.retentivity


20.The voltage induced across a certain coil is 200 mV. A 120 resistor is connected to the coil terminals. The induced current is

A.1.7 mA

B.16 mA

C.12 mA

D.120 mA


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Exercise General Questions True or False"Everything should be made as simple as possible, but not simpler."- Albert Einstein21.The induced voltage across a stationary conductor in a stationary magnetic field is

A.zero

B.reversed in polarity

C.increased

D.decreased


22.An electromagnetic field exists only when there is

A.an increasing current

B.decreasing current

C.voltage

D.current


23.When a solenoid is activated, the force that moves the plunger is

A.an electromagnetic field

B.a permanent magnetic field

C.varying voltage

D.a steady current


24.What is the magnetomotive force (mmf) of a wire with 8 turns carrying three amperes of current?

A.2,400 At

B.240 At

C.24 At

D.2.4 At


25.If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage

A.remains unchanged

B.reverses polarity

C.increases

D.decreases


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Magnetism and Electromagnetism by Pavan