Definition

1. Noun:
   • Electromagnetic phenomenon: The property of an electric circuit, especially a coil, whereby a change in the current flowing through it induces an electromotive force (EMF) or voltage within the same circuit. This induced voltage opposes the change in current that created it, in accordance with Lenz's law.
   • Quantitative measure: The phenomenon itself, or the coefficient (typically denoted by L) that quantifies it, measured in henries (H). It represents the ratio of the induced electromotive force to the rate of change of current.

Usage and Examples

• Noun:
  • The spark observed when opening a switch in a circuit with a coil is due to self-induction.
  • In designing the electromagnet, engineers had to calculate its self-induction to predict the circuit's transient behavior.
  • The self-induction of the solenoid determines how quickly the current can build up when voltage is applied.

Advanced Usage and Concepts

• "Energy stored in self-induction": The energy (½L I²) stored in the magnetic field of an inductor due to its self-induction when a current flows through it.
  • The large self-induction of the coil allows it to store a significant amount of magnetic energy.
• Role in AC circuits: Self-induction gives an inductor its property of inductive reactance (), which opposes alternating current.
  • At high frequencies, the self-induction of even a small coil can present a substantial impedance.

Variants and Related Words

• Self-inductance (n): Often used interchangeably with "self-induction," though it can more specifically refer to the quantitative coefficient .
  • The self-inductance of the loop was measured to be 5 microhenries.
• Inductor (n): A passive electrical component designed to have a specific property of self-induction.
• Mutual induction (n): The related phenomenon where a changing current in one circuit induces an EMF in a nearby, separate circuit.

Synonyms

• Inductance (when referring specifically to the property of a single, isolated coil).
• Coefficient of self-induction (formal term for the quantitative measure ).

Related Phrases and Terminology

• Back EMF: The electromotive force induced by self-induction that opposes the applied voltage.
  • The motor's self-induction generates a back EMF proportional to its rotational speed.
• LR time constant: A characteristic time (τ = L/R) that describes the rate of current change in a resistive-inductive (RL) circuit, directly dependent on self-induction.
  • The circuit's slow response is due to the large self-induction, resulting in a long time constant.

Noun

1. generation of an electromotive force (EMF) in a circuit by changing the current in that circuit; usually measured in henries