The Resonance Bridge is used to inductance measurements and needs a signal source with frequency determined by the magnitude of the measured quantities. The circuit is shown in figure bellow and there two elements to be adjusted for balance: C and R3. C4 and R4 are the capacitance and resisitance associated to the inductance to be measured.

**Formula: **

Condiction to balance:

**Where: **

ω is 2 x π x f (f is the frequency in hertz - Hz)

R1, R2, R3 and R4 are the resistances in ohm (ohms)

C is the capacitance in farads (F)

L is the inductance in henry (H)