57 + Interview Questions in Simple Magnetic Circuits in Basic Electrical Engineering Page 1 InterviewSolution

1.	The B/H ratio is not constant for ________(a) Diamagnetic materials(b) Ferromagnetic materials(c) Paramagnetic materials(d) Non-magnetic materialsThis question was addressed to me in semester exam.This is a very interesting question from Determination of the B/H Characteristic topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct choice is (b) FERROMAGNETIC materials The best EXPLANATION: As the magnetizing field increases, the relative permeability increases, REACHES a maximum, and then decreases. Due to varying permeability, B/H RATIO is not constant for ferromagnetic materials.

Discussion

2.	Calculate the magnetic flux density if the magnetic field strength is 3A/m.(a) 4pi10^-7T(b) 8pi10^-7T(c) 10pi10^-7T(d) 12pi10^-7TThis question was addressed to me in an interview for internship.Question is from Permeability of Free Space or Magnetic Constant in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Correct ANSWER is (d) 12pi10^-7T For explanation: We know that: µ0=B/H Substituting the value of H from the question, we get B = 12pi10^-7T.

Discussion

3.	Which, among the following, have negative susceptibility?(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Not a magnetic substanceThis question was addressed to me in semester exam.Question is from Permeability of Free Space or Magnetic Constant in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT option is (a) DIAMAGNETIC To explain I would say: MAGNETIC susceptibility is the degree of magnetisation of a material in response to the external magnetic field. Diamagnetic SUBSTANCES repel the magnetic field and hence have NEGATIVE susceptibility.

Discussion

4.	Magnetic field exists along which of the following?(a) Moving charges(b) Stationary charges(c) Copper(d) IronI had been asked this question by my school teacher while I was bunking the class.I would like to ask this question from Magnetomotive Force and Magnetic Field Strength topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right choice is (a) MOVING CHARGES To explain: Moving charges have a MAGNETIC field associated with them because they have magnetic flux LINES associated with it.

Discussion

5.	The ballistic galvanometer is usually lightly damped so that ________(a) It can oscillate(b) It will remain stable(c) Amplitude of the first swing is very large(d) Amplitude of the first swing is very smallThe question was posed to me in an interview for internship.Origin of the question is Determination of the B/H Characteristic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The CORRECT choice is (c) Amplitude of the first SWING is very LARGE Explanation: The BALLISTIC galvanometer is usually lightly damped so that the amplitude of its first swing is very large.

Discussion

6.	Calculate the magnetic field strength if the magnetic flux density is 4piT.(a) 10^-7/16pi^2A/m(b) 10^-7A/m(c) 10^7A/m(d) 10^-7AI got this question in examination.My doubt is from Permeability of Free Space or Magnetic Constant in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Correct CHOICE is (C) 10^7A/m The explanation: We know that: µ0=B/H Substituting the value of B from the question, we get H = 10^7A/m.

Discussion

7.	Diamagnetic substances have relative permeability_____________(a) Greater than 1(b) Less than 1(c) Equal to 1(d) ZeroThe question was asked in an interview.Asked question is from Relative Permeability in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT choice is (b) Less than 1 For explanation: A diamagnetic material CREATES a MAGNETIC FIELD OPPOSING that of the external magnetic field and it repels the external magnetic field. Hence it has relative permeability less than 1.

Discussion

8.	PMMC instruments can be used as a fluxmeters by _______(a) Using a low resistance shunt(b) Removing the control spring(c) Making the control springs having a large moment of inertia(d) Using a high resistance in seriesI had been asked this question in homework.Query is from Determination of the B/H Characteristic topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right option is (B) Removing the CONTROL SPRING The best I can explain: A PMMC or a permanent moving magnet coil INSTRUMENT can be used as a fluxmeter by removing the control spring.

Discussion

9.	A substance whose relative permeability is more than the permeability of free space is?(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Both paramagnetic and ferromagneticThis question was posed to me in my homework.This interesting question is from Relative Permeability topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct OPTION is (d) Both paramagnetic and ferromagnetic The explanation: RELATIVE permeability=1+Magnetic susceptibility Since both paramagnetic and ferromagnetic MATERIALS have positive susceptibility, their relative permeability is greater than unity i.e. their permeability is more than the permeability of FREE space.

Discussion

10.	Which among the following, is a correct expression for µ0.(a) µ0=BH(b) µ0=B/H(c) µ0=H/B(d) µ0=BH^2I got this question at a job interview.This intriguing question originated from Permeability of Free Space or Magnetic Constant topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT answer is (B) µ0=B/H Best explanation: Magnetic PERMEABILITY is the constant of proportionality between the magnetic flux DENSITY and magnetic field STRENGTH of a given medium. Hence µ0=B/H.

Discussion

11.	Magnetomotive force is equal to__________________(a) current * number of turns(b) current / number of turns(c) current / number of turns per unit length(d) current * number of turns per unit lengthI have been asked this question in an international level competition.Query is from Magnetomotive Force and Magnetic Field Strength in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right CHOICE is (a) current * NUMBER of turns For EXPLANATION: MMF is ability to produce flux and is EQUAL to product of current flowing and number of turns.

Discussion

12.	What is a PMMC instrument?(a) Permanent moving magnet coil instrument(b) Permanent machine magnet coil instrument(c) Permanent moving machine coil instrument(d) Premature moving magnet coil instrumentThis question was addressed to me in an interview for job.Question is from Determination of the B/H Characteristic topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT ANSWER is (a) Permanent moving magnet coil instrument Explanation: A PMMC instrument is a permanent moving magnet coil instrument. It uses TWO magnets to create a STATIONARY MAGNETIC field.

Discussion

13.	The unit for permeability of free space is?(a) Henry(b) Henry-m(c) Henry/m(d) Henry/m^2I have been asked this question in a job interview.This intriguing question originated from Permeability of Free Space or Magnetic Constant topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right option is (c) Henry/m For explanation I would say: Using FORMULA of SELF INDUCTANCE of solenoid, L=µ0n^2A/l We GET unit of µ0 = Henry/m.

Discussion

14.	As the magnetic field strength increases, reluctance?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI had been asked this question during an online exam.This intriguing question comes from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct option is (a) Increases The best I can EXPLAIN: RELUCTANCE is DIRECTLY proportional to the STRENGTH of the MAGNETIC field, hence as the strength of magnetic field increases, the reluctance increases.

Discussion

15.	Unit of reluctance is?(a) AWb(b) A^2/Wb(c) Wb/A(d) A/WbThe question was asked by my college director while I was bunking the class.Enquiry is from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The CORRECT CHOICE is (d) A/Wb Explanation: Reluctance is magnetomotive FORCE per unit flux, So unit of reluctance = unit of MMF / unit of magnetic flux = A/Wb.

Discussion

16.	When the area of cross section of the material increases, what happens to reluctance?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroThis question was addressed to me in an interview for internship.The above asked question is from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT ANSWER is (b) DECREASES The explanation is: Reluctance is inversely proportional to the area of CROSS section of the MATERIAL hence as area increases, reluctance decreases.

Discussion

17.	When the length of the material increases, what happens to reluctance?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI got this question in quiz.I'm obligated to ask this question of Reluctance topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct CHOICE is (a) Increases For explanation: RELUCTANCE is DIRECTLY proportional to the length of the material HENCE as length increases, reluctance also increases.

Discussion

18.	As the temperature increases beyond the Curie temperature, the relative susceptibility of ferromagnetic materials?(a) Increases(b) Decreases(c) Remains constant(d) Becomes zeroThis question was posed to me in an interview for internship.My question is taken from Relative Permeability in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» RIGHT answer is (B) Decreases Explanation: The SUSCEPTIBILITY of ferromagnetic MATERIALS increases with the increase in temperature and then it decreases when the temperature goes beyond the CURIE temperature.

Discussion

19.	Which of the following expressions is correct with respect to relative permeability?(a) B = µrµ0/H(b) B = µrµ0H(c) B = µr/µ0H(d) B = µrµ0/H^2I had been asked this question during an interview for a job.I need to ask this question from Relative Permeability topic in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right answer is (b) B = µrµ0H For EXPLANATION: For a NON magnetic material: B=µ0H. Hence for a material having RELATIVE permeability µr, B=µrµ0H.

Discussion

20.	The relation between the direction of current and the direction of magnetic field is?(a) Same direction(b) Opposite direction(c) Perpendicular(d) UnrelatedThis question was posed to me in quiz.This intriguing question comes from Magnetomotive Force and Magnetic Field Strength in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct OPTION is (c) Perpendicular The EXPLANATION is: When a conductor carries a certain VALUE of CURRENT, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.

Discussion

21.	B/H curve shows the relationship between?(a) Magnetic field strength and magnetic flux(b) Magnetic field strength and magnetic flux density(c) Current and magnetic flux density(d) Voltage and magnetic flux densityThis question was posed to me in an interview for internship.The doubt is from Determination of the B/H Characteristic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right answer is (b) Magnetic field STRENGTH and magnetic FLUX DENSITY To explain: The B/H curve shows the RELATION between magnetic field strength and magnetic flux density.

Discussion

22.	Calculate the reluctance when the magnetomotive force is 10A turns and the flux is 5Wb.(a) 0.5A/Wb(b) 5A/Wb(c) 10A/Wb(d) 2A/WbThis question was addressed to me by my school teacher while I was bunking the class.I would like to ask this question from Reluctance in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT choice is (d) 2A/Wb For explanation: We KNOW that: F=ϕ*S Substituting the GIVEN VALUES from the question: S=2A/Wb.

Discussion

23.	As the temperature increases up to the Curie temperature, the relative susceptibility of ferromagnetic materials?(a) Increases(b) Decreases(c) Remains constant(d) Becomes zeroThis question was posed to me in homework.The query is from Relative Permeability in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT choice is (a) Increases The BEST I can explain: The susceptibility of ferromagnetic materials increases with the INCREASE in TEMPERATURE and then it decreases when the temperature goes beyond the Curie temperature.

Discussion

24.	Calculate the magnetic flux density if the magnetic field strength is 2A/m.(a) 4pi10^-7T(b) 8pi10^-7T(c) 10pi10^-7T(d) 12pi10^-7TI had been asked this question in unit test.This is a very interesting question from Permeability of Free Space or Magnetic Constant in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Correct choice is (b) 8pi10^-7T Easy EXPLANATION: We know that: µ0=B/H Substituting the value of H from the QUESTION, we GET B = 8pi10^-7T.

Discussion

25.	What is the unit for relative permeability?(a) H-m(b) H/m(c) H^2/m(d) No unitThis question was posed to me in a job interview.This intriguing question comes from Relative Permeability topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» RIGHT answer is (d) No unit For explanation: Relative PERMEABILITY is the RATIO of permeability of the material to the permeability of free space. Since it is a ratio, it does not have any UNITS.

Discussion

26.	What is a permeable substance?(a) Any good conductor(b) Any bad conductor(c) Any strong magnet(d) Any substance through which the magnetic lines of force can pass easilyThe question was posed to me in my homework.Question is from Magnetomotive Force and Magnetic Field Strength in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right OPTION is (d) Any substance through which the MAGNETIC lines of FORCE can pass EASILY Explanation: A permeable substance is ONE through which the magnetic lines of force can pass easily.

Discussion

27.	A ring having a cross-sectional area of 500 mm^2, a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Calculate the flux density of the ring.(a) 1.6T(b) 2.6T(c) 3.6T(d) 4.6TThe question was asked in a national level competition.Origin of the question is Ohm’s Law for a Magnetic Circuit topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» RIGHT answer is (a) 1.6T Explanation: ϕ=BA => Flux DENSITY B = ϕ/A Substituting the VALUES, we get B=1.6T.

Discussion

28.	A substance whose relative permeability is less than the permeability of free space is?(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Not a magnetic substanceThis question was posed to me in an interview for job.I need to ask this question from Relative Permeability in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right CHOICE is (a) DIAMAGNETIC The explanation is: A diamagnetic material creates a magnetic FIELD opposing that of the external magnetic field and it repels the external magnetic field. Hence its relative permeability is less than that of the free space.

Discussion

29.	When using a fluxmeter, if the flux changes from Φ to -Φ, what happens to the current?(a) Becomes zero(b) Becomes infinity(c) Remains the same(d) ReversesThe question was asked in exam.The origin of the question is Determination of the B/H Characteristic topic in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT choice is (d) Reverses For EXPLANATION: When the FLUX changes from Φ to -Φ, the CURRENT direction will change as the direction of flux is changing.

Discussion

30.	Reluctance is ________________ to the length of the material.(a) Directly proportional(b) Inversely proportional(c) Not related(d) Reluctance is ________________ to the length of the material.The question was asked in an interview for internship.Question is taken from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct option is (a) DIRECTLY PROPORTIONAL Easiest explanation: The FORMULA for reluctance is: S = l/µ0 µr*A. From the formula, we can see that reluctance is directly proportional to the length of the MATERIAL.

Discussion

31.	Which, among the following, have positive susceptibility?(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Both paramagnetic and ferromagneticI had been asked this question during an online interview.My doubt stems from Permeability of Free Space or Magnetic Constant topic in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct choice is (d) Both PARAMAGNETIC and ferromagnetic To explain: Magnetic SUSCEPTIBILITY is the degree of magnetisation of a material in response to the EXTERNAL magnetic field. Both paramagnetic and ferromagnetic MATERIALS have POSITIVE susceptibility as they get magnetise when placed in external magnetic field.

Discussion

32.	When an electric current flows out of the page, what is the direction of the magnetic field?(a) Clockwise(b) Anti-clockwise(c) Cannot be determined(d) Parallel to the currentI had been asked this question in an online interview.My question comes from Magnetomotive Force and Magnetic Field Strength in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct option is (b) Anti-clockwise The best explanation: When the CURRENT FLOWS out of the page, the magnetic FIELD is anti-clockwise because of the right hand THUMB RULE, we orient our thumb out of the page and our fingers curl in the anti-clockwise direction.

Discussion

33.	The B/H characteristics can be determined using _______(a) Ammeter(b) Fluxmeter(c) Voltmeter(d) MultimeterThis question was posed to me by my school teacher while I was bunking the class.Origin of the question is Determination of the B/H Characteristic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right option is (b) Fluxmeter For EXPLANATION I WOULD say: The fluxmeter is an ELECTRONIC display instrument used to measure the magnetic flux of PERMANENT magnets hence it can be used to DETERMINE B/H characteristics.

Discussion

34.	The electrical equivalent of reluctance is?(a) Resistance(b) Inductance(c) Capacitance(d) ConductanceThe question was posed to me during a job interview.This key question is from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct choice is (a) Resistance Easy EXPLANATION: Resistance is the opposition to the FLOW of CHARGE, similarly reluctance is the opposition to the flow of MAGNETIC flux.

Discussion

35.	Materials having good retentivity are?(a) Strong magnets(b) Weak magnets(c) Temporary magnets(d) Permanent magnetsThe question was asked in semester exam.My question is taken from Magnetomotive Force and Magnetic Field Strength in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» CORRECT answer is (d) PERMANENT magnets For explanation: Materials with GOOD retentivity are permanent magnets because they can RETAIN magnetism even when no external magnetic field PRESENT.

Discussion

36.	A ring having a cross-sectional area of 500 mm^2, a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the magnetomotive force.(a) 1442At(b) 1342At(c) 1432At(d) 1344AtI have been asked this question in unit test.This is a very interesting question from Ohm’s Law for a Magnetic Circuit topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right answer is (d) 1344At To explain: Reluctance=L/(µA) = l/(µrµ0A) SUBSTITUTING the values, we GET Reluctance S=1.68*106 A/Wb. F=ϕS Substituting the given values, we get F = 1344At.

Discussion

37.	Calculate the MMF when the magnetic flux is 5Wb and the reluctance is 3A/Wb.(a) 10At(b) 10N(c) 15N(d) 15AtI have been asked this question in a job interview.My question is based upon Ohm’s Law for a Magnetic Circuit topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» RIGHT answer is (d) 15At For explanation: We KNOW that: F=ϕS Substituting the given VALUES from the QUESTION, we GET MMF = 15At.

Discussion

38.	What happens to the MMF when the magnetic flux decreases?(a) Increases(b) Decreases(c) Remains constant(d) Becomes zeroI have been asked this question at a job interview.The origin of the question is Ohm’s Law for a Magnetic Circuit in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right CHOICE is (b) DECREASES To elaborate: OHM’s law for the MAGNETIC circuit’s states that the MMF is DIRECTLY proportional to the magnetic flux hence as the magnetic flux decreases, the MMF also decreases.

Discussion

39.	Reciprocal of reluctance is __________(a) Permeance(b) Susceptibility(c) Resistance(d) ConductanceThe question was posed to me in unit test.My doubt stems from Reluctance topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct option is (a) PERMEANCE For explanation: The RECIPROCAL of reactance is permeance. It is the ability of a material to allow the PASSAGE of MAGNETIC lines of flux.

Discussion

40.	A substance whose permeability is less than the permeability of free space is?(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Not a magnetic substanceThis question was posed to me during an online interview.This intriguing question originated from Permeability of Free Space or Magnetic Constant in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right choice is (a) Diamagnetic Easy EXPLANATION: A diamagnetic MATERIAL creates a MAGNETIC field OPPOSING that of the external magnetic field and it repels the external magnetic field. Hence its permeability is less than that of FREE space.

Discussion

41.	Permeability of free space is also known as _________(a) Magnetic constant(b) Electric constant(c) Electrostatic constant(d) Magnetostatic constantI have been asked this question in an online interview.This is a very interesting question from Permeability of Free Space or Magnetic Constant topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Correct option is (a) Magnetic CONSTANT Easiest explanation: The permeability of FREE SPACE is also KNOWN as the magnetic constant. The permittivity of free space is the ELECTROSTATIC constant.

Discussion

42.	When a bar magnet is broken into two pieces, which of the following are true?(a) The magnet loses its magnetism(b) The magnet has only north pole left(c) The magnet has only south pole left(d) The magnet turns into two new bar magnetsI had been asked this question at a job interview.My question is based upon Magnetomotive Force and Magnetic Field Strength topic in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» RIGHT option is (d) The magnet TURNS into two NEW bar magnets Explanation: When a bar magnet is broken into two pieces, it forms two different bar magnets. This happens because the broken pieces of the magnet FORM a separate north and south pole for itself as monopoles do not exist.

Discussion

43.	Why is the coil of a ballistic galvanometer wound on a non- metallic former?(a) To minimise damping when high resistance is connected in series(b) To maximise damping when high resistance is connected in series(c) To minimise damping when high resistance is connected in parallel(d) To maximise damping when high resistance is connected in parallelI had been asked this question in an interview for job.Query is from Determination of the B/H Characteristic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct OPTION is (a) To minimise damping when high resistance is connected in series The explanation: The COIL of ma ballistic galvanometer is WOUND on a nonmagnetic former in order to minimise damping when high resistance is connected in series.

Discussion

44.	A ring having a cross-sectional area of 500 mm^2, a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the magnetising current.(a) 6.7A(b) 7.7A(c) 7.6(d) 6.1AThe question was asked in a job interview.This key question is from Ohm’s Law for a Magnetic Circuit topic in section Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right choice is (a) 6.7A For EXPLANATION: Reluctance = l/(µA) = l/(µrµ0A) SUBSTITUTING the VALUES, we get Reluctance S=1.68*106 A/Wb. F=ϕSSubstituting the given values, we get F = 1344At. I=F/NSubstituting the values from the question, we get I=6.7A.

Discussion

45.	Paramagnetic substances have relative permeability_____________(a) Greater than 1(b) Less than 1(c) Equal to 1(d) ZeroI got this question in an internship interview.Origin of the question is Relative Permeability in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right choice is (a) Greater than 1 To explain I would SAY: A PARAMAGNETIC material CREATES a magnetic field which is weakly ATTRACTED to that of the external magnetic field. Hence it has relative permeability greater than 1.

Discussion

46.	Unit of MMF is ______________(a) A/m(b) A-m(c) A(d) unitlessThe question was asked in a job interview.My question comes from Magnetomotive Force and Magnetic Field Strength topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct CHOICE is (c) A The EXPLANATION: MMF is EQUAL to the product of CURRENT flowing and number of turns. unit of Magnetomotive force = unit of current = A or ampere.

Discussion

47.	The equivalent of the current I in magnetic ohm’s law is?(a) Flux(b) Reluctance(c) MMF(d) ResistanceI got this question in unit test.My question is based upon Ohm’s Law for a Magnetic Circuit topic in division Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The CORRECT choice is (a) Flux To ELABORATE: The EQUIVALENT of current in MAGNETIC OHM’s law is flux as: V=IR is equivalent to F=ϕS.

Discussion

48.	A ring having a cross-sectional area of 500 mm^2, a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the reluctance.(a) 1.68 * 10^-4A/Wb(b) 1.68 * 10^4 A/Wb(c) 1.68 * 10^6 A/Wb(d) 1.68 * 10^-6A/WbThe question was posed to me in quiz.My query is from Ohm’s Law for a Magnetic Circuit topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Right option is (c) 1.68 * 10^6 A/Wb To EXPLAIN I WOULD say: Reluctance=l/(µA) = l/(µrµ0A) SUBSTITUTING the VALUES, we GET Reluctance=1.68*10^6 A/Wb.

Discussion

49.	When an electric current flows into the page, what is the direction of the magnetic field?(a) Clockwise(b) Anti-clockwise(c) Cannot be determined(d) Parallel to the currentThe question was asked by my college director while I was bunking the class.My doubt is from Magnetomotive Force and Magnetic Field Strength topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering
Answer» The correct option is (a) CLOCKWISE Easiest explanation: When the current flows into the page, the magnetic field is clockwise because of the right hand THUMB rule, we orient our thumb into the page and our fingers CURL in the clockwise DIRECTION.

Discussion

50.	The B/H curve can be used to determine?(a) Iron loss(b) Hysteresis loss(c) Voltage loss(d) Eddy current lossI had been asked this question during an interview.The query is from Determination of the B/H Characteristic topic in portion Simple Magnetic Circuits of Basic Electrical Engineering
Answer» Correct option is (b) Hysteresis loss Easy explanation: Hysteresis loss is basically a heat loss due to the reversal of magnetisation of the TRANSFORMER core whenever it is subjected to a changing MAGNETIC FIELD. It can be determined USING the B/H curve.

Discussion

Explore topic-wise InterviewSolutions in .

Calculate the magnetic field strength if the magnetic flux density is 4*piT.(a) 10^-7/16*pi^2A/m(b) 10^-7A/m(c) 10^7A/m(d) 10^-7AI got this question in examination.My doubt is from Permeability of Free Space or Magnetic Constant in section Simple Magnetic Circuits of Basic Electrical Engineering

Diamagnetic substances have relative permeability_____________(a) Greater than 1(b) Less than 1(c) Equal to 1(d) ZeroThe question was asked in an interview.Asked question is from Relative Permeability in portion Simple Magnetic Circuits of Basic Electrical Engineering

As the magnetic field strength increases, reluctance?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI had been asked this question during an online exam.This intriguing question comes from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering

Unit of reluctance is?(a) AWb(b) A^2/Wb(c) Wb/A(d) A/WbThe question was asked by my college director while I was bunking the class.Enquiry is from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering

When the length of the material increases, what happens to reluctance?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI got this question in quiz.I'm obligated to ask this question of Reluctance topic in portion Simple Magnetic Circuits of Basic Electrical Engineering

What is the unit for relative permeability?(a) H-m(b) H/m(c) H^2/m(d) No unitThis question was posed to me in a job interview.This intriguing question comes from Relative Permeability topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering

The electrical equivalent of reluctance is?(a) Resistance(b) Inductance(c) Capacitance(d) ConductanceThe question was posed to me during a job interview.This key question is from Reluctance topic in chapter Simple Magnetic Circuits of Basic Electrical Engineering

Materials having good retentivity are?(a) Strong magnets(b) Weak magnets(c) Temporary magnets(d) Permanent magnetsThe question was asked in semester exam.My question is taken from Magnetomotive Force and Magnetic Field Strength in chapter Simple Magnetic Circuits of Basic Electrical Engineering

Calculate the MMF when the magnetic flux is 5Wb and the reluctance is 3A/Wb.(a) 10At(b) 10N(c) 15N(d) 15AtI have been asked this question in a job interview.My question is based upon Ohm’s Law for a Magnetic Circuit topic in division Simple Magnetic Circuits of Basic Electrical Engineering

Reciprocal of reluctance is __________(a) Permeance(b) Susceptibility(c) Resistance(d) ConductanceThe question was posed to me in unit test.My doubt stems from Reluctance topic in division Simple Magnetic Circuits of Basic Electrical Engineering

Paramagnetic substances have relative permeability_____________(a) Greater than 1(b) Less than 1(c) Equal to 1(d) ZeroI got this question in an internship interview.Origin of the question is Relative Permeability in chapter Simple Magnetic Circuits of Basic Electrical Engineering

Unit of MMF is ______________(a) A/m(b) A-m(c) A(d) unitlessThe question was asked in a job interview.My question comes from Magnetomotive Force and Magnetic Field Strength topic in portion Simple Magnetic Circuits of Basic Electrical Engineering

The equivalent of the current I in magnetic ohm’s law is?(a) Flux(b) Reluctance(c) MMF(d) ResistanceI got this question in unit test.My question is based upon Ohm’s Law for a Magnetic Circuit topic in division Simple Magnetic Circuits of Basic Electrical Engineering

The B/H curve can be used to determine?(a) Iron loss(b) Hysteresis loss(c) Voltage loss(d) Eddy current lossI had been asked this question during an interview.The query is from Determination of the B/H Characteristic topic in portion Simple Magnetic Circuits of Basic Electrical Engineering

Calculate the magnetic field strength if the magnetic flux density is 4piT.(a) 10^-7/16pi^2A/m(b) 10^-7A/m(c) 10^7A/m(d) 10^-7AI got this question in examination.My doubt is from Permeability of Free Space or Magnetic Constant in section Simple Magnetic Circuits of Basic Electrical Engineering