81 + Interview Questions in Magnetostics in Electromagnetic Theory Page 2 InterviewSolution

51.	Find the Maxwell law derived from Ampere law.(a) Div(I) = H(b) Div(H) = J(c) Curl(H) = J(d) Curl(B) = DThis question was addressed to me in an interview.My question is taken from Maxwell Law in section Magnetostics of Electromagnetic Theory
Answer» The correct answer is (C) Curl(H) = J Best explanation: From the CURRENT density definition and Ohm’s law, the AMPERE CIRCUITAL law Curl(H) = J can be derived. This is Maxwell’s second law of electromagnetics.

Discussion

52.	Find the Maxwell equation derived from Faraday’s law.(a) Div(H) = J(b) Div(D) = I(c) Curl(E) = -dB/dt(d) Curl(B) = -dH/dtThis question was addressed to me in an online quiz.Question is taken from Maxwell Law in division Magnetostics of Electromagnetic Theory
Answer» CORRECT option is (c) Curl(E) = -dB/dt Easiest explanation: From the FARADAY’s law and Lenz law, using STOKE’s theorem, we get Curl(E) = -dB/dt. This is the Maxwell’s FIRST law of electromagnetics.

Discussion

53.	The divergence of which quantity will be zero?(a) E(b) D(c) H(d) BThe question was posed to me in examination.My question is from Maxwell Law in chapter Magnetostics of Electromagnetic Theory
Answer» Right answer is (d) B To EXPLAIN: The divergence of the magnetic flux density is ALWAYS zero. This is because of the non existence of magnetic MONOPOLES in a magnetic field.

Discussion

54.	Find the charge density when the electric flux density is given by 2x i + 3y j + 4z k.(a) 10(b) 9(c) 24(d) 0I have been asked this question by my school principal while I was bunking the class.My enquiry is from Maxwell Law in division Magnetostics of Electromagnetic Theory
Answer»

Discussion

55.	When the rotational path of the magnetic field intensity is zero, then the current in the path will be(a) 1(b) 0(c) ∞(d) 0.5I got this question in an internship interview.The above asked question is from Ampere Law topic in section Magnetostics of Electromagnetic Theory
Answer» The correct OPTION is (B) 0 For explanation: By Ampere law, Curl(H) = J. The rotational path of H is ZERO, implies the curl of H is zero. This shows the current density J is also zero. The current is the PRODUCT of the current density and area, which is also zero.

Discussion

56.	Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is below the sheet.(a) 6(b) 0(c) -6(d) 60kThe question was asked in an online interview.My question is from Ampere Law topic in division Magnetostics of Electromagnetic Theory
Answer» Right answer is (C) -6 To elaborate: The MAGNETIC intensity when the normal component is below the sheet is Hy = -0.5 K, where K = 12.Thus we get H = -0.5 x 12 = -6 UNITS.

Discussion

57.	Find the current density on the conductor surface when a magnetic field H = 3cos x i + zcos x j A/m, for z>0 and zero, otherwise is applied to a perfectly conducting surface in xy plane.(a) cos x i(b) –cos x i(c) cos x j(d) –cos x jThis question was posed to me in an internship interview.This key question is from Ampere Law in section Magnetostics of Electromagnetic Theory
Answer» Right option is (b) –cos X i The BEST explanation: By Ampere law, Curl (H) = J. The curl of H will be i(-cos x) – j(0) + k(-Z sin x) = -cos x i – zsin x k. In the XY plane, z = 0. Thus Curl(H) = J = -cos x i.

Discussion

58.	Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is above the sheet.(a) -6(b) 12k(c) 60(d) 6This question was addressed to me by my college director while I was bunking the class.I need to ask this question from Ampere Law topic in chapter Magnetostics of Electromagnetic Theory
Answer» The correct choice is (d) 6 Easy EXPLANATION: The magnetic field intensity when the NORMAL component is above the sheet is Hx = 0.5 K, where K = 12. THUS we get H = 0.5 X 12 = 6 units.

Discussion

59.	Calculate the magnetic field intensity due to a toroid of turns 50, current 2A and radius 159mm.(a) 50(b) 75(c) 100(d) 200This question was posed to me in an interview for job.I want to ask this question from Ampere Law in chapter Magnetostics of Electromagnetic Theory
Answer» Right option is (c) 100 The explanation is: The magnetic field INTENSITY is GIVEN by H = NI/2πrm, where N = 50, I = 2A and rm = 1/2π. Thus H = 50 x 2/2π x 0.159 = 100 units.

Discussion

60.	Find the magnetic flux density of a finite length conductor of radius 12cm and current 3A in air( in 10^-6 order)(a) 4(b) 5(c) 6(d) 7The question was asked in my homework.I want to ask this question from Ampere Law in section Magnetostics of Electromagnetic Theory
Answer» The correct option is (b) 5 Explanation: The MAGNETIC field intensity is given by H = I/2πr, where I = 3A and R = 0.12. The magnetic flux DENSITY in AIR B = μ H, where μ = 4π x 10^-7.Thus B = 4π x 10^-7 x 3/2π x 0.12 = 5x 10^-6 units.

Discussion

61.	Electric field will be maximum outside the conductor and magnetic field will be maximum inside the conductor. State True/False.(a) True(b) FalseI had been asked this question in exam.I want to ask this question from Ampere Law in portion Magnetostics of Electromagnetic Theory
Answer»

Discussion

62.	The Ampere law is based on which theorem?(a) Green’s theorem(b) Gauss divergence theorem(c) Stoke’s theorem(d) Maxwell theoremThis question was posed to me in an internship interview.I need to ask this question from Ampere Law topic in portion Magnetostics of Electromagnetic Theory
Answer»

Discussion

63.	The point form of Ampere law is given by(a) Curl(B) = I(b) Curl(D) = J(c) Curl(V) = I(d) Curl(H) = JThe question was posed to me by my school teacher while I was bunking the class.My query is from Ampere Law topic in portion Magnetostics of Electromagnetic Theory
Answer» Right option is (d) Curl(H) = J Easy explanation: Ampere LAW STATES that the line integral of H about any closed path is EXACTLY equal to the DIRECT current enclosed by that path. ∫ H.dl = I The point form will be Curl (H) = J.

Discussion

64.	The time varying electric field E is conservative. State True/False.(a) True(b) FalseThis question was posed to me during an online interview.Query is from Faraday Law, EMF and Lenz Law in section Magnetostics of Electromagnetic Theory
Answer» The correct choice is (B) FALSE Explanation: The time varying electric FIELD E(t) is not a closed path. Thus the curl will be non-zero. This IMPLIES E(t) is not conservative and the statement is false.

Discussion

65.	Which of the following statements is true?(a) E is the cross product of v and B(b) B is the cross product of v and E(c) E is the dot product of v and B(d) B is the dot product of v and EThis question was addressed to me in an internship interview.Asked question is from Faraday Law, EMF and Lenz Law topic in portion Magnetostics of Electromagnetic Theory
Answer» Right option is (a) E is the cross PRODUCT of V and B The explanation is: The electric field is the cross product of the velocity and the magnetic field intensity. This is given by Lorentz equation.

Discussion

66.	Find the displacement current when the flux density is given by t^3 at 2 seconds.(a) 3(b) 6(c) 12(d) 27I got this question by my school teacher while I was bunking the class.This key question is from Faraday Law, EMF and Lenz Law in division Magnetostics of Electromagnetic Theory
Answer» Right CHOICE is (c) 12 Easy EXPLANATION: The displacement CURRENT is given by Jd = dD/dt. Thus Jd = 3t^2. At TIME t = 2, we get Jd = 3(2)^2= 12A.

Discussion

67.	Find the force due to a current element of length 2cm and flux density of 12 tesla. The current through the element will be 5A.(a) 1 N(b) 1.2 N(c) 1.4 N(d) 1.6 NThe question was posed to me in an interview.This interesting question is from Faraday Law, EMF and Lenz Law topic in portion Magnetostics of Electromagnetic Theory
Answer»

Discussion

68.	Calculate the emf when a coil of 100 turns is subjected to a flux rate of 0.3 tesla/sec.(a) 3(b) 30(c) -30(d) -300I got this question in my homework.This interesting question is from Faraday Law, EMF and Lenz Law topic in portion Magnetostics of Electromagnetic Theory
Answer» CORRECT option is (c) -30 To ELABORATE: The induced emf is given by Vemf = -dλ/dt = -Ndψ/dt. Thus emf will be -100 X 0.3 = -30 units.

Discussion

69.	The induced voltage will oppose the flux producing it. State True/False.(a) True(b) FalseThe question was asked during an online exam.Origin of the question is Faraday Law, EMF and Lenz Law topic in division Magnetostics of Electromagnetic Theory
Answer» CORRECT choice is (a) True Easiest explanation: ACCORDING to Lenz LAW, the induced voltage acts in such a way that it opposes the FLUX producing it. This is indicated by a negative sign.

Discussion

70.	Calculate the emf when the flux is given by 3sin t + 5cos t(a) 3cos t – 5sin t(b) -3cos t + 5sin t(c) -3sin t – 5cos t(d) 3cos t + 5sin tThe question was posed to me during an internship interview.The doubt is from Faraday Law, EMF and Lenz Law in portion Magnetostics of Electromagnetic Theory
Answer» The correct ANSWER is (B) -3COS t + 5SIN t The explanation: The electromotive FORCE is given by Vemf = -dλ/dt. Thus Vemf = -dλ/dt = -(3cos t – 5sin t) = -3cos t + 5sin t.

Discussion

71.	For time varying currents, the field or waves will be(a) Electrostatic(b) Magneto static(c) Electromagnetic(d) ElectricalI got this question at a job interview.I'd like to ask this question from Faraday Law, EMF and Lenz Law topic in division Magnetostics of Electromagnetic Theory
Answer» Correct option is (c) Electromagnetic The EXPLANATION: For stationary charges, the field is electrostatic. For STEADY CURRENTS, the field is magneto static. But for time VARYING currents, the field or waves will be electromagnetic.

Discussion

72.	According to Faraday’s law, EMF stands for(a) Electromagnetic field(b) Electromagnetic force(c) Electromagnetic friction(d) Electromotive forceI have been asked this question in an interview for internship.I would like to ask this question from Faraday Law, EMF and Lenz Law topic in portion Magnetostics of Electromagnetic Theory
Answer» The CORRECT ANSWER is (d) Electromotive force For explanation: The force in any closed circuit due to the change in the FLUX LINKAGE of the circuit is called as electromotive force EMF. This phenomenon is called as Faraday’s LAW.

Discussion

73.	The magnetic field intensity will be zero inside a conductor. State true/false.(a) True(b) FalseThe question was asked in a national level competition.My enquiry is from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory
Answer» The correct CHOICE is (B) False The best explanation: Electric field will be zero inside a conductor and magnetic field will be zero outside the conductor. In other WORDS, the conductor boundary, E will be maximum and H will be minimum.

Discussion

74.	Find the magnetic flux density when a point from a finite current length element of current 0.5A and radius 100nm.(a) 0(b) 0.5(c) 1(d) 2This question was posed to me by my college professor while I was bunking the class.Question is from Biot Savart Law in chapter Magnetostics of Electromagnetic Theory
Answer» CORRECT option is (c) 1 The EXPLANATION is: The MAGNETIC flux density is B = μH, where H is given by I/2πr. Put μ = 4π x 10^-7, I = 0.5 and R = 10^-7, we get B = 4π x 10^-7 x 0.5/2π x 10^-7 = 1 unit.

Discussion

75.	The current element of the solenoid of turns 100, length 2m and current 0.5A is given by,(a) 100 dx(b) 200 dx(c) 25 dx(d) 50 dxI had been asked this question in a national level competition.My question is taken from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory
Answer» CORRECT answer is (c) 25 dx The EXPLANATION is: The CURRENT ELEMENT of the solenoid is given by NI dx/L. Put N = 100, I = 0.5 and L = 2 to get, I dx = 100 x 0.5 x dx/2 = 25 dx.

Discussion

76.	In a static magnetic field only magnetic dipoles exist. State True/False.(a) True(b) FalseThe question was posed to me during an internship interview.The query is from Biot Savart Law in section Magnetostics of Electromagnetic Theory
Answer» The correct answer is (a) True The BEST explanation: From Gauss law for magnetic FIELD, we get divergence of the magnetic flux DENSITY is always zero (IE, Div(B) = 0). This implies the non-existence of magnetic MONOPOLE.

Discussion

77.	Find the magnetic field intensity at the centre O of a square of the sides equal to 5m and carrying 10A of current.(a) 1.2(b) 1(c) 1.6(d) 1.8This question was addressed to me by my school principal while I was bunking the class.This key question is from Biot Savart Law in portion Magnetostics of Electromagnetic Theory
Answer» Correct answer is (d) 1.8 The best explanation: The magnetic FIELD is given by H = 4I/√2πω. PUT I = 10 and ω = 5m. THUS H = 4 x 10/√2π(5) = 1.8 UNIT.

Discussion

78.	Calculate the magnetic field at a point on the centre of the circular conductor of radius 2m with current 8A.(a) 1(b) 2(c) 3(d) 4I got this question in an internship interview.Enquiry is from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory
Answer» The correct CHOICE is (b) 2 Easiest EXPLANATION: The magnetic FIELD DUE to a point in the centre of the circular conductor is given by H = I/2a. Put I = 8A and a = 2m, we get H = 8/4 = 2 units.

Discussion

79.	Find the magnetic field of a finite current element with 2A current and height 1/2π is(a) 1(b) 2(c) 1/2(d) 1/4The question was posed to me in an interview.This intriguing question comes from Biot Savart Law in portion Magnetostics of Electromagnetic Theory
Answer» Correct option is (a) 1 To EXPLAIN I would say: The MAGNETIC FIELD due to a finite current element is given by H = I/2πh. Put I = 2 and h = 1/2π, we get H = 1 UNIT.

Discussion

80.	Which of the following cannot be computed using the Biot Savart law?(a) Magnetic field intensity(b) Magnetic flux density(c) Electric field intensity(d) PermeabilityI have been asked this question during an online interview.This is a very interesting question from Biot Savart Law in division Magnetostics of Electromagnetic Theory
Answer» Right CHOICE is (c) Electric FIELD intensity The explanation: The Biot SAVART law is used to calculate MAGNETIC field intensity. Using which we can calculate flux density and permeability by the FORMULA B = μH.

Discussion

81.	Biot Savart law in magnetic field is analogous to which law in electric field?(a) Gauss law(b) Faraday law(c) Coulomb’s law(d) Ampere lawI have been asked this question in a job interview.I want to ask this question from Biot Savart Law in chapter Magnetostics of Electromagnetic Theory
Answer» Right choice is (c) Coulomb’s law For explanation: Biot Savart law STATES that the magnetic flux density H = I.dl sinθ/4πr^2, which is analogous to the electric field F = q1q2/4πεr^2, which is the Coulomb’s law.

Discussion

Explore topic-wise InterviewSolutions in .

Find the Maxwell law derived from Ampere law.(a) Div(I) = H(b) Div(H) = J(c) Curl(H) = J(d) Curl(B) = DThis question was addressed to me in an interview.My question is taken from Maxwell Law in section Magnetostics of Electromagnetic Theory

Find the Maxwell equation derived from Faraday’s law.(a) Div(H) = J(b) Div(D) = I(c) Curl(E) = -dB/dt(d) Curl(B) = -dH/dtThis question was addressed to me in an online quiz.Question is taken from Maxwell Law in division Magnetostics of Electromagnetic Theory

The divergence of which quantity will be zero?(a) E(b) D(c) H(d) BThe question was posed to me in examination.My question is from Maxwell Law in chapter Magnetostics of Electromagnetic Theory

Find the charge density when the electric flux density is given by 2x i + 3y j + 4z k.(a) 10(b) 9(c) 24(d) 0I have been asked this question by my school principal while I was bunking the class.My enquiry is from Maxwell Law in division Magnetostics of Electromagnetic Theory

When the rotational path of the magnetic field intensity is zero, then the current in the path will be(a) 1(b) 0(c) ∞(d) 0.5I got this question in an internship interview.The above asked question is from Ampere Law topic in section Magnetostics of Electromagnetic Theory

Calculate the magnetic field intensity due to a toroid of turns 50, current 2A and radius 159mm.(a) 50(b) 75(c) 100(d) 200This question was posed to me in an interview for job.I want to ask this question from Ampere Law in chapter Magnetostics of Electromagnetic Theory

Find the magnetic flux density of a finite length conductor of radius 12cm and current 3A in air( in 10^-6 order)(a) 4(b) 5(c) 6(d) 7The question was asked in my homework.I want to ask this question from Ampere Law in section Magnetostics of Electromagnetic Theory

Electric field will be maximum outside the conductor and magnetic field will be maximum inside the conductor. State True/False.(a) True(b) FalseI had been asked this question in exam.I want to ask this question from Ampere Law in portion Magnetostics of Electromagnetic Theory

The Ampere law is based on which theorem?(a) Green’s theorem(b) Gauss divergence theorem(c) Stoke’s theorem(d) Maxwell theoremThis question was posed to me in an internship interview.I need to ask this question from Ampere Law topic in portion Magnetostics of Electromagnetic Theory

The point form of Ampere law is given by(a) Curl(B) = I(b) Curl(D) = J(c) Curl(V) = I(d) Curl(H) = JThe question was posed to me by my school teacher while I was bunking the class.My query is from Ampere Law topic in portion Magnetostics of Electromagnetic Theory

The time varying electric field E is conservative. State True/False.(a) True(b) FalseThis question was posed to me during an online interview.Query is from Faraday Law, EMF and Lenz Law in section Magnetostics of Electromagnetic Theory

Find the displacement current when the flux density is given by t^3 at 2 seconds.(a) 3(b) 6(c) 12(d) 27I got this question by my school teacher while I was bunking the class.This key question is from Faraday Law, EMF and Lenz Law in division Magnetostics of Electromagnetic Theory

Calculate the emf when a coil of 100 turns is subjected to a flux rate of 0.3 tesla/sec.(a) 3(b) 30(c) -30(d) -300I got this question in my homework.This interesting question is from Faraday Law, EMF and Lenz Law topic in portion Magnetostics of Electromagnetic Theory

The induced voltage will oppose the flux producing it. State True/False.(a) True(b) FalseThe question was asked during an online exam.Origin of the question is Faraday Law, EMF and Lenz Law topic in division Magnetostics of Electromagnetic Theory

Calculate the emf when the flux is given by 3sin t + 5cos t(a) 3cos t – 5sin t(b) -3cos t + 5sin t(c) -3sin t – 5cos t(d) 3cos t + 5sin tThe question was posed to me during an internship interview.The doubt is from Faraday Law, EMF and Lenz Law in portion Magnetostics of Electromagnetic Theory

For time varying currents, the field or waves will be(a) Electrostatic(b) Magneto static(c) Electromagnetic(d) ElectricalI got this question at a job interview.I'd like to ask this question from Faraday Law, EMF and Lenz Law topic in division Magnetostics of Electromagnetic Theory

The magnetic field intensity will be zero inside a conductor. State true/false.(a) True(b) FalseThe question was asked in a national level competition.My enquiry is from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory

The current element of the solenoid of turns 100, length 2m and current 0.5A is given by,(a) 100 dx(b) 200 dx(c) 25 dx(d) 50 dxI had been asked this question in a national level competition.My question is taken from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory

In a static magnetic field only magnetic dipoles exist. State True/False.(a) True(b) FalseThe question was posed to me during an internship interview.The query is from Biot Savart Law in section Magnetostics of Electromagnetic Theory

Calculate the magnetic field at a point on the centre of the circular conductor of radius 2m with current 8A.(a) 1(b) 2(c) 3(d) 4I got this question in an internship interview.Enquiry is from Biot Savart Law topic in portion Magnetostics of Electromagnetic Theory

Find the magnetic field of a finite current element with 2A current and height 1/2π is(a) 1(b) 2(c) 1/2(d) 1/4The question was posed to me in an interview.This intriguing question comes from Biot Savart Law in portion Magnetostics of Electromagnetic Theory

Biot Savart law in magnetic field is analogous to which law in electric field?(a) Gauss law(b) Faraday law(c) Coulomb’s law(d) Ampere lawI have been asked this question in a job interview.I want to ask this question from Biot Savart Law in chapter Magnetostics of Electromagnetic Theory