Wheatstone bridge is an important device used in the measurement of medium resistances. (Ranges from 1 to 0.1M). The Wheatstone’s bridge is an instrument for making comparison measurements and operates upon a null indication principle. This means the indication is independent of the calibration of the null indicating instrument or any of its characteristics. Accuracy of 0.1% is quite common with a Wheatstone bridge as opposed To accuracy’s of 3% to 5% with ordinary ohmmeter for measurement of medium resistance. This trainer requires an optional external DMM to measure the NULL balance in Voltage mode. This has 3 decades of variable resistance as one arm of the bridge. Built-in power supplies. Using single strand patch cords does the experiment.

This trainer has all the components required to study by experiment the principles of Wheatstone’s bridge measurement as stated above.

Bridge used for the measurement of self - inductance in terms of comparison with a standard capacitance and non-inductive resistance, using the following equation. This bridge has the capability to measure inductance in the range of 350mH – 2H
Lx = C (R3/R4) [R (R4+R2)+R2R4]

In this bridge we are having three sections. A built in oscillator section. A bridge section with six arms. Arm AC consists of non-inductive resistance R3. Arm AD consists of fixed capacitance .Arm CB consists of unknown inductance (Lx). Arm BE consists of non-inductive resistance R2. Arm AE consists of non-inductive resistance R4. Arm DE consists of variable resistance R. The balance of bridge can be observed using a built-in audio amplifier with loudspeaker arrangement. This acts as a null detector.

In this trainer you will measure the unknown values of Capacitance, in terms of two non-inductive resistance. The balance of bridge can be observed using a built-in audio amplifier with loudspeaker arrangement. This acts as a null detector. This bridge has the capability to measure unknown capacitance in the range of
Cx = C1 (R4/ R3)

Cx = capacitor whose capacitance is to be measured
C1 = a standard capacitor this capacitor is either an air or gas capacitor and Hence is loss free. However, if necessary, a correction may be made for the loss angle of this capacitor. R3 is a non-inductive resistor with multiple range of selection. R4 is a variable non- inductive resistor. The balance of bridge can be observed using a built-in audio amplifier with loudspeaker arrangement. This acts as a null detector.

Owen’s Bridge is used for the measurement of inductance in terms of capacitance using the following equations. Since an inductor has both reactive (inductance) and a resistive (capacitance) component, at least two measurements are required. This bridge has the capability to measure inductance in the range of 1mH – 9H
Lx = R2 R3 C4
Rx = R3 (C4/C2)

In this bridge we are having three sections. A built in oscillator section. Bridge section with four arms. Arm AC consists of multiple selection of resistance (R1) & unknown inductance. Arm AD consists of Variable resistance R2, & fixed capacitor of value 0.1?f. Arm CB consists of resistance R3 with multiple selection ranges. Arm BD consists of fixed capacitor of value about 0.1?f. the balance of bridge can be observed using a built-in audio amplifier with loudspeaker arrangement. This acts as a null detector.

Kelvin Double Bridge is used to measure the value of low resistance of the order of 1? . In our set up the range is from 1? to 120 ?. Kelvin Bridge is a modification of Whetstone Bridge and provides greatly increased accuracy in measurement of low value of resistance. Kelvin Double Bridge incorporates the idea of a second set of ratio arms (hence the name double bridge) use of four

terminal resistors for the low resistance arms. This bridge is used for the measurement of unknown resistance in terms of comparison with a standard capacitance using the following equation
Cx = C3 (R1/R2)
In this bridge we are having three sections. A built in oscillator section. Bridge section with four arms. Arm AC consists of standard fixed capacitance. Arm AD consists of unknown capacitance Cx. Arm DB consists of non-inductive resistance R2 with multiple range of selection. Arm BC consists of parallel network between variable resistance R1 of 10k? & variable capacitance of (100 – 1KPF). The balance of bridge can be observed using a built-in audio amplifier with loudspeaker arrangement. This acts as a null detector.
Ranges of Measurement is from (0.1µFD – 0.001µFD)

Methods for Measurement of Low Resistance
•Ammeter Voltmeter Method
•Kelvins Double Bridge Method
•Potentiometer Method