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(a) Derive the condition of balance for Wheatstone bridge.

(b) Draw the circuit diagram of a meter bridge to explain how it is based on Wheatstone bridge.

 

 
 
 
 
 

Answers (1)

a) 

To obtain the balancing condition of Wheatstone bridge;
Applying Kirchoff's loop Rule to ABDA, we have        
I_{1}p+I_{g}G-I_{2}R= 0
where G is galvanometer resistance.
Now Applying Kirchoff's loop Rule to BCDB.we have
                 
     
\left ( I_{1}-I_{g} \right )Q-\left ( I_{2}+I_{g} \right )S-GI_{g}= 0

when the bridge is balanced, I_{g}= 0
then, the equation can be written as:-

I_{1}p-I_{2}R= 0 \: or\: I_{1}p= I_{2}R----(1)

I_{1}Q-I_{2}S= 0 \: or \: I_{1}Q= I_{2}S----(2)


On dividing equation (1) by (2),we get


\frac{\not{I}_{1}P}{\not{I}_{1}Q}-\frac{\not{I}_{2}R}{\not{I}_{2}S}= 0
\frac{P}{Q}-\frac{R}{S}= 0
\frac{P}{Q}= \frac{R}{S}, 

Which is the balanced condition of a Wheatstone bridge.

b) 

Posted by

Safeer PP

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