Basics of Current: Practice Problem & Solution
A copper wire of radius 1 mm contains \(10^{22}\) free electrons per cubic metre. The drift velocity for free electrons when 10 A current flows through the wire will be (Given, charge on electron \(= 1.6 \times 10^{-19} \text{C}\))
Solution Explained:
To solve this problem, we apply the core principles of Basics of Current. Understanding the underlying formula is key to arriving at the correct answer below:
Using \(I = n e A v_d ⇒ v_d = \frac{I}{n e \pi r^2}\). Substituting values, we get \(v_d = \frac{10}{10^{22} \times 1.6 \times 10^{-19} \times \pi \times (10^{-3})^2} = \frac{6.25}{\pi} \times 10^3 \text{ms}^{-1}\).
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