From Faraday's Law, we learned that a changing magnetic field creates a curly electric field. As a similar parallel, we are now saying that a changing electric field (with time) creates a curly magnetic field. Conveniently, we already have an equation that describes a curly magnetic field: Ampere's Law.
From Faraday's Law, we learned that a changing magnetic field creates a curly electric field. As a similar parallel, we are now saying that a changing electric field (with time) creates a curly magnetic field. Conveniently, we already have an equation that describes a curly magnetic field: Ampere's Law.
∫→B∙d→l=μ0Ienc
∫→B∙d→l=μ0Ienc
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This term that we added to Ampere's Law functions in much the same way as Faraday's law. If we can calculate the changing electric flux through a loop, then we can use that to find the magnetic field that curls around that loop. In the example below, we use a charging capacitor to illustrate how this can done; however, for the purposes of this class, we will primarily rely on this idea conceptually (rather than asking you to calculate the magnetic field from a changing electric flux).
This term that we added to Ampere's Law functions in much the same way as Faraday's law. If we can calculate the changing electric flux through a loop, then we can use that to find the magnetic field that curls around that loop. In the example below, we use a charging capacitor to illustrate how this can done; however, for the purposes of this class, we will primarily rely on this idea conceptually (rather than asking you to calculate the magnetic field from a changing electric flux).
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==== Why this Matters ====
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===== Why this Matters =====
With this final piece of the puzzle, we can actually say something really important about how electric and magnetic fields work. If we //__assume that there are no current-carrying wires nearby__//, then we have a set of two equations that say that:
With this final piece of the puzzle, we can actually say something really important about how electric and magnetic fields work. If we //__assume that there are no current-carrying wires nearby__//, then we have a set of two equations that say that:
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==== Examples ====
==== Examples ====
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[[:184_notes:examples:Week14_b_field_capacitor|Magnetic Field from a Charging Capacitor]]
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* [[:184_notes:examples:Week14_b_field_capacitor|Challenge: Magnetic Field from a Charging Capacitor]]
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* Video Example: Magnetic Field from a Charging Capacitor