# Can I measure resistance of an inductor on a bridge?

I designed a circuit to have a Q-factor of 15, knowing the inductor value I rearranged the equation $\omega_o=\frac{1}{\sqrt{LC}}$ to give me a capacitor value for a certain resonant frequency. When I built the final RCL circuit, the Q factor was found to be way out (using $\frac{\omega}{\Delta\omega}$) with a Q factor <7.

I am told this is due to the resistance in say the signal generator, cabling etc and also the inductor. Is it ok to measure the inductor on a bridge using the resistor setting so it gives a value in ohms? Or am I going about this Q factor error the wrong way?

• Yes you have to include the 50 ohm gen source impedance for any frequency and coax. capacitance of 100pF/m and probe resistance. time to re-do calculations. You can measure R of an inductor with an DMM which is ok for lower frequency where skin effect is not too significant. Otherwise corrections for skin effects is needed. Good RLC meters apply a CC sine wave and measure voltage amplitude and phase shift to calculate parameters for 120Hz 1kHz up to 1MHz. – Sunnyskyguy EE75 Feb 15 '17 at 23:18

The circuit at left has an inductor whose self-resistance yields a Q of 15 at resonance. Yet the resonant voltage across R2 yields a $\frac{\omega}{\Delta\omega}$ loaded Q much less, because total R is now 171 ohms.