Question

The drift velocity of electrons in a silver wire with cross–sectional area 3.14×10⁻6m² carrying a current of 20A is to be calculated. Given: atomic weight of Ag =108, density of silver =10.5×10³kg m⁻3.

• A. \(2.798\times10^{-4}\,\text{m s}^{-1}\)
• B. \(67.98\times10^{-4}\,\text{m s}^{-1}\)
• C. \(0.67\times10^{-4}\,\text{m s}^{-1}\)
• D. 6.798×10⁻4m s⁻1

Hint:

Drift velocity is extremely small even for large currents.

Answer 1

The Correct Option is D

Step 1: Drift velocity formula: vd = (I)/(nqA)
Step 2: Number density of electrons: n = (ρ NA)/(M) = frac10.5×10³ × 6.02×10²3108×10⁻3
Step 3: Substituting values: vd = \frac20n(1.6×10⁻19)(3.14×10⁻6) ≈ 6.798×10⁻4m s⁻1