ElectroMagnetic Theory Concepts & Solved Numericals

1. Define A Uniform Plane Wave. Answer: In an uniform plane wave the electric and magnetic field vectors both lie in a plane and all such planes are parallel to each other. Also the amplitude and phase of vectors E and H are constant over the planes & they are always normal to the direction pf propagation. 2. State Gauss Divergence Theorem. Answer: This theorem states that the net flux of a vector field F over any closed surface S is equal to the volume integral of the divergence of that vector field over the volume enclosed by the surface S . Mathematically it is expressed as: 3. State Stoke’s Theorem. Answer: This theorem states that the line integral of vector field A around the closed curve forming the periphery of any surface S is equal to surface integral of the curl of that vector field taken over surface S bound by the curve forming periphery of the surface. Mathematically it is expressed as: 4. What Do You Understand By Displacement Current...

01. State Three Ways In Which Forces Due To Magnetic Fields Can Be Experienced? Answer: There are at least three ways in which force due to magnetic fields can be experienced. The force can be due to a moving charged particle in a magnetic field. on a current element in an external magnetic field. between two current elements. 02. State The Lorentz Force Equation? Answer: The Lorentz force equation relates the force acting on a particle with charge Q in the presence of EM fields. It expresses the fundamental law relating EM to mechanics. F = Q(E + u * B) = m ( du/dt) Based on the Lorentz force law, the force experienced by a current element Idl in a magnetic field B is dF = I dl * B From this, the magnetic field B is defined as the force per unit current element. 03. Define Magnetic Torque? Answer: The torque T (or mechanical moment of force) on the loop is the vector product of the force F and iho moment arm r. T = r X F and magnetic torque is meas...

01. How Can Materials Be Classified In Terms Of Their Electrical Properties? Answer:  Materials can be classified roughly as conductors (σ >> 1, ε r = 1) and dielectrics ( σ << 1, ε r  ≥ 1 ) in terms of their electrical properties  σ  and  ε r  where  σ  is the conductivity and  ε r  is the dielectric constant or relative permittivity. A material with high conductivity ( σ >> 1) is referred to as a metal whereas one with low conductivity ( σ << 1 ) is referred to as an insulator. A material whose conductivity lies somewhere between those of metals and insulators is called a semiconductor. 02. Define Superconductor? Answer: The conductivity of metals generally increases with decrease in temperature. At temperatures near absolute zero (T = 0°K), some conductors exhibit infinite conductivity and are called superconductors. Lead and aluminum are typical examples of such metals. 03. Why...

1. What Do You Mean By Dielectric Constant Of A Material ? Answer: Dielectric constant (k) or relative permittivity (ε r ) is defined as the ratio of capacitance of a capacitor with dielectric to the capacitance of same capacitor without dielectric. It generally describes the ability of a material to polarize and store a charge. Mathematically, k or ε r = C/C 0 . [Since C = q/V, we have ε r = E 0 /E = V 0 /V = ε/ε r ]. 2. Define Dielectric Medium. Answer: Dielectric is a material in which energy can be stored by the polarization of the molecules. It is a material that increases the capacitance or charge storage ability of a capacitor. Ideally, a dielectric is an insulator and does not contain free charge. However, in the presence of external field it exhibits a relative displacement of opposite bound charges and hence the polarization of the medium. Due to polarization induced surface charges tend to weaken the original field within the dielectric. [The resultan...