TS EAMCET · Physics · Current Electricity
An aluminium (resistivity \(\rho=2.2 \times 10^{-8} \Omega\)-m) wire of a diameter \(1.4 \mathrm{~mm}\) is used to make a \(4 \Omega\) resistor. The length of the wire is
- A \(220 \mathrm{~m}\)
- B \(1000 \mathrm{~m}\)
- C \(280 \mathrm{~m}\)
- D \(1 \mathrm{~m}\)
Answer & Solution
Correct Answer
(C) \(280 \mathrm{~m}\)
Step-by-step Solution
Detailed explanation
Length of the wire is \(\begin{array}{rl}\quad l & =\frac{R A}{\rho} \\ \therefore \quad l & l \\ \therefore \quad & \frac{4 \times \pi \times\left(0.7 \times 10^{-3}\right)^2}{2.2 \times 10^{-8}} \\ & =280 \mathrm{~m}\end{array}\)
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