Glossary
Angular Frequency (ω)
The rate of oscillation in an LC circuit, measured in radians per second, determined by the values of inductance (L) and capacitance (C) as ω = 1/√(LC).
Example:
To tune an LC circuit to a higher radio frequency, you would need to adjust the components to achieve a larger angular frequency (ω).
Energy Stored in an Inductor (U)
The potential energy stored within the magnetic field created by the current flowing through an inductor, given by the formula U = ½LI².
Example:
A large electromagnet stores significant energy stored in an inductor (U), which is released as heat when the current is turned off.
Henries (H)
The SI unit of inductance, representing one Weber per Ampere (Wb/A).
Example:
A typical power supply filter might use an inductor with an inductance of several Henries (H) to smooth out voltage ripples.
Induced EMF (ε)
The electromotive force generated across an inductor due to a change in the magnetic flux through it, which opposes the change in current according to Faraday's Law.
Example:
When you quickly disconnect a motor, the collapsing magnetic field in its windings creates a large induced EMF (ε) that can cause a spark.
Inductance (L)
A measure of an inductor's ability to oppose changes in current, defined as the proportionality constant between magnetic flux and current.
Example:
A large inductance (L) in a choke coil means it will strongly oppose rapid changes in current, making it useful for filtering AC signals.
Inductor
A passive electrical component, typically a coil of wire, that resists changes in current by storing energy in a magnetic field.
Example:
An inductor in a car's ignition system helps smooth out current spikes, ensuring a steady spark plug firing.
LC Circuit
An electrical circuit consisting of only an inductor and a capacitor, where energy oscillates sinusoidally between the electric field of the capacitor and the magnetic field of the inductor.
Example:
Radio tuners often use an LC circuit to select a specific frequency, as the circuit resonates at a particular angular frequency.
LR Circuit
An electrical circuit consisting of a resistor and an inductor, where the current and voltage change exponentially over time when a voltage is applied or removed.
Example:
A simple LR circuit can be used as a timing circuit, where the time it takes for the current to reach a certain level is predictable.
Lenz's Law
A fundamental principle stating that the direction of an induced current or EMF is always such that it opposes the change in magnetic flux that produced it.
Example:
If you try to push a magnet into a coil, Lenz's Law dictates that the induced current will create a magnetic field that repels the magnet, resisting its entry.
Magnetic Flux (ΦB)
A measure of the total number of magnetic field lines passing through a given area, representing the amount of magnetic field passing through a surface.
Example:
As a magnet moves through a coil, the changing magnetic flux (ΦB) through the coil induces a current.
Time Constant (τ)
A characteristic time for an LR circuit, equal to L/R, representing the time it takes for the current or voltage to reach approximately 63.2% of its final value during transient behavior.
Example:
A short time constant (τ) in an LR circuit means the current will reach its steady state very quickly.