Calculating unknown resistances by wheatstone bidge, Physics

Calculating unknown resistances

The current through the galvanometer (G) - a very sensitive ammeter, is reduced to zero by adjusting R4.  The bridge is then said to be balanced.  When the bridge is balanced, the voltage at A is equal to the voltage at B and no current flows between A and B.

424_wheat stone bridge.png

 

Hence       VR1             =       VR2

          therefore   I1 ´ R1           =       I2 ´ R2 ------------- (1)  (by Ohm's law)

          Also           VR3             =       VR4

          therefore   I1 ´ R3        =       I2 ´ R4 ------------- (2)

 

 

Dividing (1) by (2) 1368_Calculating unknown resistances.png

 

Therefore the unknown resistor  R3  = 1887_Calculating unknown resistances1.png    (all known values)

In calculations it is possible for any of the four resistors to be unknown.  However, provided that the bridge is balanced, the theory remains the same and all that is required is to transpose the equation to find the unknown 

 

Posted Date: 9/13/2012 3:51:58 AM | Location : United States







Related Discussions:- Calculating unknown resistances by wheatstone bidge, Assignment Help, Ask Question on Calculating unknown resistances by wheatstone bidge, Get Answer, Expert's Help, Calculating unknown resistances by wheatstone bidge Discussions

Write discussion on Calculating unknown resistances by wheatstone bidge
Your posts are moderated
Related Questions
Derive mathematical equation for an electromagnetic wave travelling in a charge free conducting medium in terms of electric field vector.

Majority and minority charge carriers  A pure semiconductor has equal number of holes and electrons. But an extrinsic semiconductor has majority charge carriers. When a tri

Reducing friction with ball bearings  Find two tin cans that have a deep groove approximately the top, such as paint cans. Lay marbles in single groove and invert the other can

1. What evidence suggests that light is a wave? What evidence suggests that light is a particle? 2. In what sense does the "information age" depend on the bending of light?

In order to obtain p-type germanium it should be doped with a (A) Trivalent impurity.      (B) Tetravalent impurity. (C) Pentavalent impurity. (D) Any of the above will d

What is the difference between an artificial satellite and a natural satellite? Ans) 1:artificial satellites are man made while natural satellite are formed by nature. 2:artificia

A sodium cation has different number of electrons from: (1) O 2-                  (2) F -       (3) Li +                    (4) Al +3 Ans: Li +

How is sensitive flame method used for detection of ultrasonic waves? Sensitive flame method: A narrow sensitive flame is shifted along the medium. At the situations of anti

why raise in ppotential is taken as positive

Define the function of photodetectors in fibre optic communication system. Photo-detectors: At the receiver end, conversion of optical signal into analog signal is being don