JEE Mains · Physics · STD 12 - 3. current electricity
A uniform wire of length \(l\) and radius \(r\) has a resistance of \(100\, \Omega \). It is recast into a wire of radius \(\frac{r}{2}\). The resistance of new wire will be ............... \(\Omega\)
- A \(1600\)
- B \(400\)
- C \(200\)
- D \(100\)
Answer & Solution
Correct Answer
(A) \(1600\)
Step-by-step Solution
Detailed explanation
Given, \({R_1} = 100\,\Omega ,{r^\prime } = r/2,{R_2} = ?\) Resistivity of wire, \(\mathrm{R}=\frac{\rho l}{\mathrm{A}}\) \(\because\) Area \(\times\) length \(=\) volume Hence, \(R=\frac{\rho V}{A^{2}}\) since, \(\rho \rightarrow\) constant, \(V \rightarrow\) constant…
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