Question Detail
Question
In a charging RC circuit, what fraction of the maximum charge does the capacitor acquire after one time constant (τ)?
Correct Answer
Option C is the correct answer.
Detailed Explanation
Page 21 states that after one time constant, the 'Charge on capacitor plates rises to ~64% of maximum value'. Mathematically, at t = τ, q(τ) = Qmax (1 - e⁻¹) ≈ Qmax (1 - 0.3678) ≈ 0.632 Qmax.
Hint
Use the formula q(t) = Qmax (1 - e⁻ᵗ/ᴿᶜ) and substitute t = τ.