Inductance
Understanding inductance and its unit, the Henry.
What is Inductance?
Inductance is the property of an electrical conductor by which a change in current flowing through it induces an electromotive force (voltage) in the conductor itself (self-inductance) or in a neighboring conductor (mutual inductance). It is a measure of how much magnetic flux is produced per unit of current.
The Henry (H)
The Henry (symbol: H) is the SI unit of inductance, named after Joseph Henry. One Henry is defined as the inductance of a closed circuit in which an electromotive force of one volt is produced when the electric current in the circuit varies uniformly at one ampere per second.
Common Sub-units of Henry
Since the Henry is a relatively large unit, inductance values are often expressed in smaller sub-units:
| Unit | Symbol | Conversion to Henrys |
|---|---|---|
| Millihenry | mH | 1 mH = 10-3 H |
| Microhenry | µH | 1 µH = 10-6 H |
| Nanohenry | nH | 1 nH = 10-9 H |
Relationship with Voltage and Current Change
Where:
• V = Induced Voltage (Volts)
• L = Inductance (Henrys)
• dI/dt = Rate of change of current (Amperes per second)
Frequently Asked Questions
What is the difference between inductance and an inductor?
Inductance is a property of a circuit element, while an inductor is the physical component designed to possess a specific amount of inductance.
How does inductance affect AC circuits?
In AC circuits, inductors exhibit inductive reactance, which opposes changes in current. This property is frequency-dependent and causes the current to lag behind the voltage.