Anderson's bridge is used to self inductance of a coil

1. Anderson’s Bridge
Mrs.P.Kanmani,
Assistant Professor,
Department of Physics,
V.Vanniaperumal Collegefor Women,
Virudhunagar.

2. Anderson’s Bridge
Principle:
The bridge circuits are used to measure various component values like
resistance, capacitance, inductance, etc. The simple form of a bridge circuit consists
of a network of four resistances/impedance arms that forms a closed circuit. A
current source is applied to two opposite nodes and a current detector is connected
to the remaining two nodes.

3. Anderson’sBridge
Principle:
The bridge circuits use the null indication principle and comparison measurement
method, this is also known as “Bridge Balance condition at zero voltage. The bridge
circuit compares the values of an unknown component with that of an accurately known
standard component. Thus, the accuracy mostly depends on the bridge circuit, not on the
null-indicator.
Anderson's Bridge, in fact, is a modification of Maxwell's inductance
capacitance bridge. In Anderson's Bridge, the self inductance is measured in terms of a
standard capacitor.

4. Anderson’s Bridge
L =self-inductanceto bemeasuredhenry,
S’=resistanceof self-inductor in ohm,
S=resistanceconnected in serieswith
self-inductor in ohm,
P,Q,R =known non-inductive resistances
in ohm, and
C=fixed standardcapacitor
L =C[r(R+S+S’)+QR] henry

5. Anderson’s Bridge
Aim :
Todeterminetheself inductance of
thecoil (L) usingAnderson’s bridge.
Apparatus :
Resistance boxes,capacitance, Self
inductance to bemeasured,Head phone.

6. Anderson’s Bridge
Procedure:
Connections are made as shown in the
theory. A.C. source say a 1000Hz audio-oscilloscope and a
head set is used here. Keeping the value of P, Q, R and S
constant, adjust the value of variable resistance r till the
sound is reduced to a minimum value. This is the balancing
point of the alternating current. Note the value of
resistance r and capacitor C. Repeat the experiment with
differenct P
,Q and R,S values and calculate the self
inductanceof the coilusing equation.

7. Anderson’s Bridge
Table :
S.NO P = Q R in
oh
m
S in
ohm
r in ohm L = C[r (R+S+S’)+QR] in henry
Result :
TheSelf inductanceof the givencoil=---------------