Question

For two resistance wires joined in parallel, the resultant resistance is $\frac{6}{5}\Omega$ .When one of the resistance wires breaks the effective resistance becomes $2\Omega$.The resistance of the broken wire is :

• A. $\frac{3}{5}\Omega$
• B. $2\Omega$
• C. $\frac{6}{5}\Omega$
• D. $3\Omega$

Answer 1

The correct option is D $3\Omega$

Suppose resistance of wires are $R_1$ and $R_2$ then

$\frac{6}{5}=\frac{R_1{R}_2}{R_1+R_2}$. If $R_2$ breaks then

$R_1=2\Omega$

Hence, $\frac{6}{5}=\frac{2\times R_2}{2+R_2}\Rightarrow R_2=3\Omega$.