Question

I want conclusion on physics meter bridge project

Answer 1

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. it was invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843.Although today digital multimeters provide the simplest way to measure a resistance, The Wheatstone Bridge can still be used to measure very low values of resistances down in the milli-Ohms range.



Wheatstone Bridge



Principal For Wheat Stone Bridge
The general arrangement of Wheatstone bridge circuit is shown in the figure below. It is a four arms bridge circuit where arm AB, BC, CD and AD are consisting of electrical resistances P, Q, S and R respectively. Among these resistances P and Q are known fixed electrical resistances and these two arms are referred as ratio arms. An Galvanometer is connected between the terminals B and D through a switch K2. The voltage source of this Wheatstone bridge is connected to the terminals A and C via a switch K1 as shown. A variable resistor S is connected between point C and D. The potential at point D can be varied by adjusting the value of variable resistor. If we vary the electrical resistance value of arm CD the value of current I2 will also be varied as the voltage across A and C is fixed. If we continue to adjust the variable resistance one situation may comes when voltage drop across the resistor S that is I2.S is becomes exactly equal to voltage drop across resistor Q that is I1.Q. Thus the potential at point B becomes equal to the potential at point D hence potential difference between these two points is zero hence current through galvanometer is nil. Then the deflection in the galvanometer is nil when the switch K2 is closed.

Applying Kirchoff’Law we can easily find that in that condition

P/Q=R/S

Answer 2

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. it was invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843.Although today digital multimeters provide the simplest way to measure a resistance, The Wheatstone Bridge can still be used to measure very low values of resistances down in the milli-Ohms range.