Kankeshwaridevi Institute of Tech. Name of Students:rajput rahulsinh Enrollment no : Subject Code : Name Of Subject : Engineering Electromagnetics Name of Unit :Magnetostatics Topic:Magnetostatics Name of Faculty : Mrunali Patel
Four laws of electromagnetism
Electrostatics Charges make E fields and forces charges make scalar potential differences dV E can be found from V Electric forces move charges Electric fields store energy (capacitance)
Magnetostatics Currents make B fields currents make magnetic vector potential A B can be found from A Magnetic forces move charges and currents Magnetic fields store energy (inductance)
Electrodynamics Changing E(t) make B(x) Changing B(t) make E(x) Wave equations for E and B Electromagnetic waves Motors and generators Dynamic Sun
Vector Analysis Dot product: A. B = A x B x + A y B y + A z B z = A B cos Cross product: |AxB| = A B sin
Examples of vector products Dot product: work done by variable force Cross product: angular momentum L = r x mv
Differential operator “del” Del differentiates each component of a vector. Gradient of a scalar function = slope in each direction Divergence of vector = dot product = what flows out Curl of vector = cross product = circulation
Practice: 1.15: Calculate the divergence and curl of v = x 2 x + 3xz 2 y - 2xz z Ex: If v = E, then div E = charge; if v = B, then curl B = current.
Separation vector differs from position vector: Position vector = location of a point with respect to the origin. Separation vector: from SOURCE (e.g. a charge at position r’) TO POINT of interest (e.g. the place where you want to find the field, at r).
Electrostatics: charges make electric fields Charges make E fields and forces charges make scalar potential differences dV E can be found from V Electric forces move charges Electric fields store energy (capacitance)
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