JNTU
JNTU B.Tech II ELECTROMAGNETIC FIELDS Previous Question Paper (March - 2022 - R16)
Answer any five questions. All questions carry equal marks.
Main
Derive the expression for Electric Field due to Sheet of charge.
Answer
Consider an infinite sheet of charge in the xy-plane with a uniform surface charge density ρs (C/m2). By symmetry, the electric field must be directed normal to the sheet, i.e., in the ±z direction. Applying Gauss's Law to a Gaussian pillbox extending from z = -h to z = h with cross-sectional area A:
The flux through the side walls is zero since the field is parallel to the walls. The flux through the two end caps is:
Solving for the electric field intensity E = D/ε0:
where an is the unit vector normal to the sheet, pointing away from the surface.
A charge Q2 = 121 nC is located in vacuum at P2(-0.03, 0.01, -0.04). Find force on Q2 due to Q1 = 100 µC at P1(0.03, 0.08, 0.02). All distances in meters.
Answer
Given Q1 = 100 × 10-6 C at P1(0.03, 0.08, 0.02) and Q2 = 121 × 10-9 C at P2(-0.03, 0.01, -0.04). The distance vector r12 from P1 to P2 is:
The magnitude |r12| is:
Using Coulomb's Law, the force F on Q2 is:
Substituting the values (1/4πε0 ≈ 9 × 109):
What is the significance of Laplace’s Equation? Also obtain the solution of Laplace’s equation in one variable.
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Derive the expression for torque on a electric dipole in a electrostatic field.
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Define capacitance and derive the expression for the capacitance of Co-axial capacitor with composite dielectric.
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State and explain about Ohm’s law in Point form.
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Obtain the expression for MFI due to Solenoid in a current carrying wire by applying Biot-Savort’s law.
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A current element I·Δl = 2π(0.6ax - 0.8ay) is situated at a point (4, -2, 3). Find the incremental field at ΔH at point (1, 2, 3).
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State and explain Ampere Circuital Law with any one application.
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Explain about Point form of Ampere Circuital law.
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Explain how a differential current loop acts as magnetic dipole.
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Derive the expression for Force between two straight long and parallel current carrying conductor.
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What is polarization? Explain.
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Obtain the boundary conditions for dielectric-dielectric media in electrostatic fields?
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Write the Modified Maxwell’s equations for time varying fields.
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Explain Faraday’s laws of electromagnetic Induction.
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