TS EAMCET · Physics · Current Electricity
The electric resistance of a certain wire of iron is \(R\). If its length and radius are both doubled, then
- A The resistance will be doubled and the specific resistance will be halved.
- B The resistance will be halved and the specific resistance will remain unchanged.
- C The resistance will be halved and the specific resistance will be doubled.
- D The resistance and the specific resistance, both will remain unchanged.
Answer & Solution
Correct Answer
(B) The resistance will be halved and the specific resistance will remain unchanged.
Step-by-step Solution
Detailed explanation
\[ \begin{aligned} & \text { (b) } \mathrm{R}^{\prime}=\frac{\rho \mathrm{L}}{\mathrm{A}} \\ & =\frac{\rho \times 2 \mathrm{~L}}{\pi(2 \mathrm{r})^2}=\frac{2 \rho \mathrm{L}}{\pi \times 4 \mathrm{r}^2}=\frac{\mathrm{R}}{2} \end{aligned} \] Hence, the resistance will be halved…
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