**BM1251 ELECTRIC FIELDS AND MACHINES 3 1 0 100**

**AIM**

To give the necessary background to understand various laws and equations governing electric and magnetic fields.

**OBJECTIVES**

• To study in detail the steady electric field and steady magnetic field.

• To understand the variation in the equations while analysing the electric / magnetic field in time varying condition from the steady state condition.

• To study the measurements to be made to access the electrical parameters related to both electric and magnetic field.

• To understand the working of various electrical machines in both AC and DC excitation.

**1. STATIC ELECTRIC FIELD 8**

Coulomb’s Law, Electric field intensity, Gauss’s law and its applications, Permittivity, Polarisation, Boundary relation, Capacitance, Dielectric strength, Energy and energy density, Poisson’s and Laplace equations and applications, Electric Current, Current Density, Ohms law at a point, Resistance and Conductance, Continuity relations for current, Problems.

**2. STEADY MAGNETIC FIELD 8**

The Biot- Sawart law, Gauss’s law for magnetic fields, Torque on a loop, Ampere’s law and magnetic field intensity, Magnetic materials, Magnetic dipoles, Loops and Solenoids, Magnetization, Inductance, Energy in an Inductor and Energy Density, Boundary relations, Ferro magnetism, Hysteresis, Reluctance and Permeance, Problems.

**3. TIME VARYING ELECTRIC AND MAGNETIC FIELDS 7**

Faraday’s law, Transformer and Motional Induction, Maxwell’s equation from Faraday’s law, Self and Mutual Inductance, Displacement current, Maxwell’s equation from Ampere’s law and its in consistency, Boundary relation, Poynting Vector, Comparison of field and circuit theory, Circuit application of Pointing Vector.

**4. ELECTRICAL CIRCUITS 7**

Ohms law, Kirchoffs law, Steady State solution of DC circuits, Introduction to AC circuits, waveforms and RMS value, Power and Power factor, Single Phase and 3 Phase balanced circuits, Power measurement.

**5. ELECTRICAL MACHINES 10**

Principles of Operation and characteristics of Transformers (Single – Phase and Three – Phase), DC Machines, Synchronous Machines, 3 Phase and Single Phase Induction Motors, (op. principles).

**6. ELECTRICAL MEASUREMENTS: 5**

Moving coil and Moving Iron Instruments (Ammeter and Voltmeter), Dynamometer type watt meters and energy meters (op.principles).

**TUTORIAL 15**

**TOTAL : 60**

**TEXT BOOK**

1. John D.Krauss, “Electromagnetics”, McGraw-Hill, 1999

**REFERENCE**

1. Hayt.W.H, “Engineering Electromagnetics”, McGraw-Hill, 1995.

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