Measuring Inductance in an LR Circuit with AC

In summary, in an LR circuit with alternating current, a 2 ohm resistor is used to measure the inductance of the cable which is of the order 10^-7. This measurement can be done at two frequencies, 100kHz and 1MHz. The 1MHz frequency is better because the order of magnitude of reactance is comparable to that of the resistor, resulting in a clearer measurement of the phase shift between current and voltage. This is due to the fact that the impedance of an inductance is higher at higher frequencies, making the 1MHz frequency more suitable for this measurement.
  • #1
momomo_mo
25
0
In an LR circuit with alternating current , it is know that the inductance of the cable is of the order 10^-7 . With a 2 ohm resistor ,the circuit is used to measure inductance.There are 2 frequencies , 100kHZ and 1M Hz,that can be chosen for the measurement .
So whyI MHz is better . I know that it is because order of magnitude of reactance is comparable to that of resistor.But why is it better ??

Thanks!
 
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  • #2
It would be clearer if you provided details of the measurement method. If you are looking at the phase shift between the current and voltage, then it is easiest to measure when the resistance and reactance are comparable.
 
  • #3
I see your point.Thanks
 
  • #4
The impedance of an inductant depends on the frequency, the higher the frequency, the larger the impedance. In your case, the inductance of the cable is of the order 10^-7 which is quite low, so we should use the 1MHz frequency for measuring to have better output.
 

1. What is inductance in an LR circuit with AC?

Inductance is a property of an electrical circuit that describes the ability of the circuit to store energy in the form of a magnetic field. It is denoted by the symbol L and is measured in units of henries (H).

2. How do you measure inductance in an LR circuit with AC?

To measure inductance in an LR circuit with AC, a device called an inductance meter or an LCR meter is used. This device sends a known AC current through the circuit and measures the resulting voltage. By using the ratio of voltage to current, the inductance can be calculated.

3. What is the role of AC in measuring inductance in an LR circuit?

AC, or alternating current, is used in measuring inductance in an LR circuit because it allows for the magnetic field to constantly change. This changing magnetic field induces a voltage in the circuit, which can be measured and used to calculate the inductance.

4. How does the resistance in an LR circuit affect the measurement of inductance?

The resistance in an LR circuit can affect the measurement of inductance by causing the voltage and current to be out of phase. This can lead to errors in the calculation of inductance. To minimize these errors, the resistance should be kept as low as possible.

5. What are some common applications of measuring inductance in an LR circuit with AC?

Inductance measurements in LR circuits are commonly used in the design and testing of electronic circuits, such as filters, amplifiers, and power supplies. They are also used in the study of electromagnetic fields and in the development of wireless communication technologies.

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