Question 695: Current Electricity

Question

Three resistances, P, Q, R each of 2$$\Omega $$ and an unknown resistance S from the four arms of a Wheatstone bridge circuit. When a resistance of 6 $$\Omega $$ is connected in parallel to S the bridge gets balanced. What is the value of S?

Accepted Answer

A balanced wheatstone bridge simply requires
$${P \over Q} = {R \over S} \Rightarrow {2 \over 2} = {2 \over S}$$
Therefore, S should be 2$$\Omega $$.
A resistance of 6$$\Omega $$ is connected in parallel.
In parallel combination,
$${1 \over R} = {1 \over {{R_1}}} + {1 \over {{R_2}}}$$
$${1 \over 2} = {1 \over 6} + {1 \over S}$$
$$ \Rightarrow S = 3\Omega $$

Answer

3 $$\Omega $$

Answer

6 $$\Omega $$

Answer

1 $$\Omega $$

Answer

2 $$\Omega $$.

Current Electricity

Three resistances, P, Q, R each of 2$\Omega and an unknown resistance S from the four arms of a Wheatstone bridge circuit. When a resistance of 6 \Omega $ is connected in parallel to S the bridge gets balanced. What is the value of S?

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