JNTU
JNTU B.Tech II Year ELECTROMAGNETIC FIELDS Previous Question Paper (May/June - 2019 - R16)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
PART A
State Coulumb’s Law and mention its limitations.
Answer
Coulomb's Law states that the force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them, acting along the line joining them. Its limitations include that it is strictly valid only for point charges at rest and in free space.
Two infinite plane sheets of equal charge densities 1 C/m2 are placed at (0,0,0) and (0,0,3) respectively. Find the Electric field intensity at (0,0,2).
Answer
The electric field intensity due to an infinite sheet of charge is given by E = ρs / (2ε0) in the direction normal to the sheet. For the sheet at z=0, the field at z=2 is (1 / 2ε0) az. For the sheet at z=3, the field at z=2 is (1 / 2ε0) (-az) because the point is below the sheet. The total field is the sum: (1 / 2ε0) az - (1 / 2ε0) az = 0 V/m.
Define conduction and convection current densities.
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Mention the properties of a conductor.
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State Gauss’s law for magnetostatic fields.
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Prove Curl (H)=Jc
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Write the units of magnetic scalar and vector and scalar potentials.
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What does Lorentz force equation specify?
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Express relation between (i) electric field intensity and magnetic field intensity for time varying field (ii) displacement current density and electric flux density.
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Define statistically induced emf and dynamically induced emf.
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PART B
Obtain the expression for electric field intensity and potential due to an electric dipole.
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Find the total charge Q within the sphere of radius r=4 m if its volume charge density is ρv = C/m3.
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State and derive the expression for Equation of continuity.
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Explain the concept of polarization of dielectrics.
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Derive the expression for electrostatic energy density.
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A homogeneous dielectric (Ɛr= 2.5) fills region 1 (x<0) while region 2 (x>0) is free space. If D1=12 ax-10 ay+4 az nC/m2, find D2.
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Obtain the expression for capacitance of a spherical capacitor.
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State the boundary conditions in electrostatic fields and prove any one of them.
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Apply Biot-Savart’s law to derive the expression for Magnetic Field Intensity due to circular loop placed on xy plane with radius ‘r’.
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If magnetic vector potential is 2.5 r az Wb/m in free space, find Magnetic field intensity.
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Define Magnetic flux, Magnetic flux line and Magnetic flux density and state the relation between Magnetic flux and Magnetic flux density.
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Planes z = 0 and z = -10 m carry currents with K = -100ax A/m and K = 60ax A/m respectively. Determine H at the point (-2, -3, -1)m.
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Derive the expression for the force between two finite current carrying loops.
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Derive the expression for self-inductance of a toroid.
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Derive the expression for energy stored and density in a magnetic field.
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Define and explain Scalar Magnetic potential and its limitations.
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Write Maxwell’s equations for time varying fields and make their word statements.
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Given E and H in free space, find parameters.
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In a material for which σ = 5 S/m and εr = 1.0, the electric field intensity is given by E = 250 Sin(1010 t) V/m. Find the conduction and displacement current densities.
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State and explain Faraday’s laws of electromagnetic induction with its integral and point forms.
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