mutual inductance

Examples of mutual inductance in the following topics:

• Inductance

  • where M is defined to be the mutual inductance between the two devices.
  • The larger the mutual inductance M, the more effective the coupling.
  • A large mutual inductance M may or may not be desirable.
  • We want a transformer to have a large mutual inductance.
  • Units of self-inductance are henries (H) just as for mutual inductance.

• Inductance

  • Mutual inductance is the effect of Faraday's law of induction for one device upon another, such as the primary coil in transmitting energy to the secondary in a transformer.
  • where M is defined to be the mutual inductance between the two devices.
  • The larger the mutual inductance M, the more effective the coupling.
  • Transformers run backward with the same effectiveness, or mutual inductance M.
  • Their mutual inductance M indicates the effectiveness of the coupling between them.

• RL Circuits

  • Recall that induction is the process in which an emf is induced by changing magnetic flux.
  • Mutual inductance is the effect of Faraday's law of induction for one device upon another, while self-inductance is the the effect of Faraday's law of induction of a device on itself.
  • An inductor is a device or circuit component that exhibits self-inductance.
  • The characteristic time $\tau$ depends on only two factors, the inductance L and the resistance R.
  • The greater the inductance L, the greater it is, which makes sense since a large inductance is very effective in opposing change.

• Faraday's Law of Induction and Lenz' Law

  • This relationship is known as Faraday's law of induction.
  • The minus sign in Faraday's law of induction is very important.
  • As the change begins, the law says induction opposes and, thus, slows the change.
  • This is one aspect of Lenz's law—induction opposes any change in flux.
  • Express the Faraday’s law of induction in a form of equation

• Changing Magnetic Flux Produces an Electric Field

  • Faraday's law of induction states that changing magnetic field produces an electric field: $\varepsilon = -\frac{\partial \Phi_B}{\partial t}$.
  • We have studied Faraday's law of induction in previous atoms.
  • In a nutshell, the law states that changing magnetic field $(\frac{d \Phi_B}{dt})$ produces an electric field $(\varepsilon)$, Faraday's law of induction is expressed as $\varepsilon = -\frac{\partial \Phi_B}{\partial t}$, where $\varepsilon$ is induced EMF and $\Phi_B$ is magnetic flux.
  • Therefore, we get an alternative form of the Faraday's law of induction: $\nabla \times \vec E = - \frac{\partial \vec B}{\partial t}$.This is also called a differential form of the Faraday's law.
  • Faraday's experiment showing induction between coils of wire: The liquid battery (right) provides a current which flows through the small coil (A), creating a magnetic field.

• Sound Systems, Computer Memory, Seismograph, GFCI

  • The microphone works by induction, as the vibrating membrane induces an emf in a coil.
  • The speaker is then driven by modulated electrical currents (produced by an amplifier) that pass through and magnetize (by inductance) a speaker coil of copper wire, creating a magnetic field.
  • This is done by inductance.

• Induced Charge

  • Electrostatic induction is the redistribution of charges within an object that occurs as a reaction to the presence of a nearby charge.
  • Electrostatic induction is the redistribution of charge within an object, which occurs as a reaction to a nearby charge.

• Energy Stored in a Magnetic Field

  • A simple generator uses inductance to create a current by the rotation of a magnet within a coil of wire.
  • If the current changes, the change in magnetic flux is proportional to the time-rate of change in current by a factor called inductance (L).
  • (Eq. 1), where L is the inductance in units of Henry and I is the current in units of Ampere.

• RLC Series Circuit: At Large and Small Frequencies; Phasor Diagram

  • Response of an RLC circuit depends on the driving frequency—at large enough frequencies, inductive (capacitive) term dominates.
  • If the frequency is high enough that XL is much larger than R as well, the impedance Z is dominated by the inductive term.

• Motional EMF

  • As seen in previous Atoms, any change in magnetic flux induces an electromotive force (EMF) opposing that change—a process known as induction.
  • Motion is one of the major causes of induction.
  • When flux changes, an EMF is induced according to Faraday's law of induction.
  • To find the magnitude of EMF induced along the moving rod, we use Faraday's law of induction without the sign: