Answer 1

Given:-

Area of the plates, A = 20 cm² = 20 × 10⁻⁴ m²

Separation between the plates, d = 1 mm = 1 × 10⁻³ m,

Resistance of the circuit, R = 10 kΩ

The capacitance of a parallel-plate capacitor,

\[C = \frac{\in_0 A}{d}\]

\[   = \frac{8 . 85 \times {10}^{- 12} \times 20 \times {10}^{- 4}}{1 \times {10}^{- 3}}\]

\[   = \frac{8 . 85 \times {10}^{- 12} \times 2 \times {10}^{- 4}}{{10}^{- 3}}\]

\[   = 17 . 7 \times  {10}^{- 12}   F\]

Time constant = CR

= 17.7 × 10⁻¹² × 10 × 10³

= 17.7 × 10⁻⁸ s

= 0.177 × 10⁻⁶ s

= 0.18 μs