JEE Mains · Physics · STD 12 - 3. current electricity
Two wires of same length and thickness having specific resistances \(6\, \Omega \,cm\) and \(3 \,\Omega\, cm\) respectively are connected in parallel. The effective resistivity is \(\rho\, \Omega \,cm\). The value of \(\rho\) to the nearest integer, is ..... .
- A \(2\)
- B \(8\)
- C \(6\)
- D \(4\)
Answer & Solution
Correct Answer
(D) \(4\)
Step-by-step Solution
Detailed explanation
\(\because\) in parallel \(R _{ net }=\frac{ R _{1} R _{2}}{ R _{1}+ R _{2}}\) \(\frac{\rho \ell}{2 A }=\frac{\rho_{1} \frac{\ell}{ A } \times \rho_{2} \frac{\ell}{ A }}{\rho_{1} \frac{\ell}{ A }+\rho_{2} \frac{\ell}{ A }}\) \(\frac{\rho}{2}=\frac{6 \times 3}{6+3}=2\) \(\rho=4\)
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