How to Measure Inductance of a Coil

Inductance can be measured using simple laboratory equipment.
••• Hemera Technologies/PhotoObjects.net/Getty Images

Inductors are sometimes wound by the user instead of bought. In such cases, the inductance would not be stamped on the side but instead may need to be found empirically. The best way to measure inductance for an inductor like a coil (solenoid) is to use an inductance bridge or meter. If you have neither, a more indirect way is to use an oscilloscope.

    Connect a resistor of known resistance and the coil in series with the sine wave oscilloscope.

    Turn on the oscilloscope and clamp the two clips of one voltmeter to the circuit on opposite sides of the coil to determine the voltage drop across the coil. Then do the same for the resistor with another voltmeter.

    Set the frequency of the oscilloscope such that the voltage drop across the resistor and inductor are the same. Finding said frequency may be a matter of trial and error. At that frequency, the resistance of the resistor and the impedance of the inductor will be equal.

    Set the resistor’s resistance and the inductor’s impedance equal to each other and solve for the inductance of the coil. Resistance = 2?fL, where \"f\" is the frequency of the oscilloscope and \"L\" is the coil’s inductance. The resistance of the resistor has not changed from the start; it is independent of the frequency. So \"L\" can be solved for by arithmetic.

    Things You'll Need

    • Sine-wave oscilloscope
    • 2 voltmeters
    • Resistor of known resistance to close tolerance

Related Articles

How to Calculate the Henrys in a Coil
How to Find Wattage With Voltage & Frequency
How to Measure the Ohm Value for an Inductor
How to Convert Hertz to Motor Rpm
How to Determine the Primary & Secondary of a Transformer
How to Design an RC Snubber
How to Calculate Millivolts from Microsiemens
How to Calculate Induced Armature Voltage
How to Use a Multimeter for the Beginner
How to Calculate DC Voltage
What Is DC & AC Resistance?
How to Convert Amps to HP
How to Calculate the Inductance of a Ferrite Inductor
What Is a Varactor Diode?
Types of Electrical Transformers
How to Calculate KVA to MVA
How to Change Electrical Amps to Watts
How to Calculate the Field Current in a DC Motor
How to Convert a 9V Battery to 3.3V DC
How to Calculate Ohms to Microfarads