Wheatstone Bridge Circuit Diagram, Applications, Formula - Class 12, JEE & NEET
Wheatstone Bridge
Principle of Wheatstone Bridge
Balanced Wheatstone Bridge
Unbalanced Wheatstone Bridge
Applications of Wheatstone Bridge
Kelvin's Double Bridge
The Wheatstone Bridge circuit is nothing more than two simple series-parallel arrangements of resistances connected between a voltage supply terminal and ground producing zero voltage difference between the two parallel branches when balanced. Here we will study about, Wheatstone Bridge, the Conditions of balanced and Unbalanced Wheatstone bridge circuit Diagram, and its applications.
It is an arrangement of four resistances devised by Charles Wheatstone which is used to measure an unknown resistance.
The Wheatstone bridge principle states that if four resistances P, Q, R, and S are arranged to form a bridge with a cell and key between A and C, and a galvanometer between B and D then the bridge is said to be balanced when the galvanometer shows a zero deflection.
In balanced condition$\mathrm{I}_{9}=0 \quad$ so $\mathrm{V}_{\mathrm{B}}=\mathrm{V}_{\mathrm{D}}$ or $\frac{P}{Q}=\frac{R}{s}$. This is called condition of balance.
The condition of balance depends on resistance P, Q, R, and S. This is independent of the emf of the battery.
In-state of balance, the cell and galvanometer can be interchanged. While performing an experiment at start press the cell key $K_{c}$ first and then the galvanometer key $\mathrm{K}_{9}$ and at end remove $\mathrm{K}_{9}$ first and then $\mathrm{K}_{\mathrm{c}}$ to avoid induced effects.
P and Q are called ratio arms, R is the known resistance arm and S is the unknown arm. BD and AC are called conjugate arms.
The resistance of a balanced Wheatstone bridge between A and C is $\frac{(P+Q)(R+S)}{P+Q+R+S}$.
The sensitivity of the bridge depends upon the value of resistances. The sensitivity is maximum when P, Q, R, and S are of the same order.
If $\frac{P}{Q}<\frac{R}{s}$ then $V_{B}>V_{D}$ so current flows from $B$ to $D .$
If $\frac{P}{Q}>\frac{R}{s}$ then $V_{B}< span> so current flows from $D$ to $B$
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The Wheatstone Bridge has many uses in electronic circuits other than comparing an unknown resistance with a known resistance. When used with Operational Amplifiers, the Wheatstone bridge circuit can be used to measure and amplify small changes in resistance, RX due.
Wheatstone bridge is not suitable for measurement of very small and very high resistances. Very low resistances are measured by Kelvin's double bridge while very high resistances by leakage method.
For Complete Study Material and Video Tutorials for JEE & NEET Exam Preparation Download eSaral APP Also Read:
Types and Effects of Electric Current
Ohm's Law and Resistance
Combination of Resistances
EMF and Internal Resistances of a Cell
Cells Connected in Series, parallel and Mixed
Kirchhoff's Circuit Law
Electric Currents in Conductors
Moving Coil galvanometer
Ammeter and Voltmeter
Potentiometer Working Principle
Wheatstone Bridge Balanced Wheatstone Bridge Unbalanced Wheatstone Bridge Applications of Wheatstone Bridge Kelvin's Double Bridge
Vidhi sindher
Sept. 12, 2020, 11:07 p.m.
Aacha sa explan kiya hua tha issa
Sept. 7, 2020, 6:45 p.m.
It was very understandable , and help me a lot