The number density of electron in copper is `8.5 xx10^(28)m^(-3)`. Find the current flowing through a copper wire of length 20 cm, area of cross section is 1 mm square,when connected to a battery of 3 V. Given the electron mobility `=4.5xx10^(-6)m^(2)V^(-1) s^(-1)` and electron charge `=1.6 xx 10^(-19)C`.

Explanation

To find the current flowing through a copper wire, we will use the following steps:

### Step 1: Convert all given quantities to SI units.
- Length of the wire, \( L = 20 \, \text{cm} = 0.2 \, \text{m} \)
- Area of cross-section, \( A = 1 \, \text{mm}^2 = 1 \times 10^{-6} \, \text{m}^2 \)
- Potential difference, \( V = 3 \, \text{V} \)
- Electron mobility, \( \mu = 4.5 \times 10^{-6} \, \text{m}^2 \, \text{V}^{-1} \, \text{s}^{-1} \)
- Electron charge, \( e = 1.6 \times 10^{-19} \, \text{C} \)
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