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What is meant by time varying field?
The fields which are produced due to the time varying currents are called time varying fields or dynamic fields. The fields which do not change with respect to time are called static fields or time invariant fields.
What is meant by transformer emf?
An emf generated when a stationary closed path is placed in a time varying magnetic field B vector is called transformer emf or statically induced emf.
What is meant by electromagnetic induction?
When closed path is moved in a magnetic field, a current is generated and thus emf is generated. Similarly when a closed path is kept steady and the magnetic field is varied, the current is produced hence emf is generated. This phenomenon is known as an electromagnetic induction.
State Maxwell’s fourth equation.
The net magnetic flux emerging through any closed surface is zero.
State Maxwell’s Third equation
The total electric displacement through the surface enclosing a volume is equal to the total charge within the volume.
What is the significant of displacement current?
The displacement current is associated with the time varying electric fields. It always exists in all imperfect conductors which carry time varying conduction current.
Write Maxwell’s equation in differential form.
Write Maxwell’s equation in Integral form.
Write time harmonic Maxwell’s equation in phasor form.
What is meant by motional emf?
An emf induced in a closed path when it is moved in a constant and time variant magnetic field is called motional emf.
Write an expression for displacement current density.
Write the significance of displacement current.
The displacement current is associated with the time varying electric fields. It always in all imperfect conductors which carry time varying conduction current.
Write the statement for Maxwell’s equation derived from faraday’s law.
The total electromagnetic force induced in a closed path is equal to the negative surface integral of the rate of change of flux density with respect to time over an entire surface bounded by the same path.
Write the statement for Maxwell’s equation derived from Gauss’s law for electric field.
The total flux leaving out of a closed surface is equal to the total charge enclosed by a finite volume.
Write the statement for Maxwell’s equation derived from Gauss’s law for magnetic field.
The surface integral of magnetic flux density over a closed surface is always equal to zero.
State faraday’s law of electromagnetic induction.
The electromotive force (emf) induced in a closed path is proportional to rate of change of magnetic flux enclosed by the closed path
Faraday’s law can be stated as
e= -N (d∅)/dt
Write expression for conduction and displacement current densities.
Conduction current density Jc= σE
Displacement current density JD = ∂D/∂t = ε ∂E/∂t
Define poynting vector.
If the E and H are the time varying electric and magnetic field respectively, then the cross product of E and H is called poynting vector P
P=E × H
State poynting theorem.
The poynting theorem is based on law of conservation of energy in electromagnetism. The poynting theorem states that the net power flowing out of a given V is equal to a time rate of decrease in the energy stored within volume V minus ohmic power dissipated.
Write expression for average and complex poynting vector.
P = 1/2 E×H^*
P = 1/2 Re(E ×H)