JEE Mains · Physics · STD 12 - 3. current electricity
A wire of resistance \(R\) and radius \(r\) is stretched till its radius became \(r / 2\). If new resistance of the stretched wire is \(xR\), then value of \(x\) is _______.
- A \(15\)
- B \(16\)
- C \(17\)
- D \(18\)
Answer & Solution
Correct Answer
(B) \(16\)
Step-by-step Solution
Detailed explanation
We know \(\mathrm{R}=\frac{\rho l}{\mathrm{~A}}, \mathrm{R} \propto \frac{l}{\mathrm{r}^2}\) As we starch the wire, its length will increase but its radius will decrease keeping the volume constant \(\mathrm{V}_{\mathrm{i}}=\mathrm{V}_{\mathrm{f}}\)…
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