JEE MAIN - Physics (2006 - No. 37)
In a Wheatstone's bridge, three resistance $$P, Q$$ and $$R$$ connected in the three arms and the fourth arm is formed by two resistances $${S_1}$$ and $${S_2}$$ connected in parallel. The condition for the bridge to be balanced will be
$${P \over Q} = {{2R} \over {{S_1} + {S_2}}}$$
$${P \over Q} = {{R\left( {{S_1} + {S_2}} \right)} \over {{S_1}{S_2}}}$$
$${P \over Q} = {{R\left( {{S_1} + {S_2}} \right)} \over {2{S_1}{S_2}}}$$
$${P \over Q} = {R \over {{S_1} + {S_2}}}$$
解释
$${P \over Q} = {R \over S}$$ where $$S = {{{S_1}{S_2}} \over {{S_1} + {S_2}}}$$