What Is the Unit of Inductance (Henry) & How Does It Work?

[Mr_Bojingles]

I read that the unit of inductance is the measure of the time it takes for a current to fully establish itself through the inductor.

When a battery is connected across a wire-coil inductor (or any kind of inductor), it
takes a while for the current flow to establish itself throughout the inductor. The current
changes at a rate that depends on the inductance: the greater the inductance, the
slower the rate of change of current for a given battery voltage.
The unit of inductance is an expression of the ratio between the rate of current
change and the voltage across an inductor. An inductance of one henry, abbreviated H,
represents a potential difference of one volt across an inductor within which the current
is increasing or decreasing at one ampere per second.

Is the reason it takes longer in some inductors for the current to establish itself because it creates a greater magnetic flux? Can the henry also tell you the intensity of the magnetic field produced in an inductor? Obviously a coil with 10 turns is going to have a greater magnetic flux than one with 5 turns. If I took the iron core out of the 10 turn coil would the current flow faster because there would be less back EMF? Is that the idea behind it? Wouldn't it be easier to measure an inductors inductance by measuring the magnetic flux created when current flows through it?

Have I got the right idea of the henry or am I mixing something up?

 

[berkeman]

You have the basic ideas correct. And the L value is generally easiest to measure by putting an AC voltage across the inductor, and measuring the resulting current. Measuring the flux directly is a more difficult physical problem.

 

[ravenprp]

You have the right idea of the henry, but there are a few additional points to consider. One of the main factors that affects the time it takes for current to establish itself in an inductor is the inductance value itself. The higher the inductance, the longer it will take for the current to reach its maximum value. This is because inductance is essentially a measure of the opposition to change in current flow. So, in a high inductance inductor, the change in current will be slower compared to a low inductance inductor.

The reason for this is indeed related to the creation of a magnetic field. When current flows through a wire, a magnetic field is created around it. In an inductor, this magnetic field is enhanced by the presence of a core material, such as iron. This core material helps to concentrate and strengthen the magnetic field, which in turn increases the inductance. So, removing the core material from a 10-turn coil would reduce the inductance and therefore, the time it takes for the current to establish itself.

The henry can also tell you the intensity of the magnetic field produced in an inductor, as it is directly related to the inductance value. However, measuring inductance by measuring the magnetic flux can be difficult and less accurate compared to using other methods such as measuring the time it takes for the current to reach a certain value.

Overall, the henry is a unit that represents the ability of an inductor to store energy in the form of a magnetic field and resist changes in current flow. It is an important concept in understanding the behavior of inductors and their applications in circuits.