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Wheatstone Bridge Calculator
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Wheatstone bridge named after Sir Charles Wheatstone is an electric circuit as the name suggests is in a shape of a bridge, the bridge is nothing but a galvanometer.It helps in finding the unknown resistance value of a resistor.

Lets consider the circuit
Wheatstone Bridge
The unknown resistance is given by
Rx = $\frac{R_b \times R_c}{R_a}$
The bridge voltage is given by
Vb = Vin $\times$ ($\frac{R_x}{R_x + R_c}$ - $\frac{R_b}{R_b+R_a}$)
Wheat stone bridge is a online tool to calculate the unknown variable unknown resistance either of Rx, Ra or Rb and output voltage vo. You just have to enter the given quantities and get these unknown ones.
 

Steps for Wheatstone Bridge Calculator

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Step 1 :  

Read the given problem and observe the given quantities.



Step 2 :  

To find the unknown resistance use the formula


Rx = $\frac{R_b R_c}{R_a}$


Where Ra, Rb and Rc are given quantities


To find the bridge voltage use the formula


Vb = Vi $\times$ ($\frac{R_x}{R_x + R_c}$ - $\frac{R_b}{R_b + R_a}$)


Substitute the values in the above formula and get the answer.



Problems on Wheatstone Bridge Calculator

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  1. In a wheat stone bridge circuit the 12 V is given as input. If three resistances have values as 30 $\Omega$, 50 $\Omega$ and 70 $\Omega$. Calculate the unknown resistance Rx and ouput voltage Vo.


    Step 1 :  

    Given: Resistance Ra = 30 $\Omega$, Rb = 50 $\Omega$, Rc = 70 $\Omega$


        


     



    Step 2 :  

    The unknown resistance Rx is given by


    Rx = $\frac{R_b R_c}{R_a}$


         = $\frac{50 \times 70}{30}$


         = 116.66 $\Omega$


        $\approx$ 117 $\Omega$


    vb = vin ($\frac{R_x}{R_c + R_x}$ - $\frac{R_b}{R_a + R_b}$)
       = 12 ($\frac{117}{117 + 70}$ - $\frac{50}{50 + 30}$)
       = 12 (0.6266 - 0.625)
       = 12 $\times$ 0.000668
       = 0.008 V.



    Answer  :  

    The unknown resistance is Rx = 117 $\Omega$ and Vb = 0.008 V.



  2. In a wheat stone bridge circuit if three resistances have values as 20 $\Omega$, 40 $\Omega$ and 60 $\Omega$. If the   bridge is balanced calculate the unknown resistance Rx


    Step 1 :  

    Given: Resistance R1 = 20 $\Omega$, R2 = 40 $\Omega$, R3 = 60 $\Omega$



    Step 2 :  

    The unknown resistance is


    Rx = $\frac{R_b R_c}{R_a}$


         = $\frac{40 \times 60}{20}$


         = 120 $\Omega$



    Answer  :  

    The unknown resistance Rx is 120 $\Omega$.



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