What is Capacitance?
Capacitance is the ability of a capacitor to store electrical charge. It depends on the physical characteristics of the capacitor, including the area of the plates, the distance between them, and the permittivity of the dielectric material between the plates.
Formula
The capacitance C of a parallel plate capacitor is given by:
$$C = \frac{\varepsilon \times A}{d}$$
Where:
- C = Capacitance (Farads)
- ε = Permittivity of the dielectric material (F/m)
- A = Area of one plate (m²)
- d = Separation distance between plates (m)
Example Calculation
Calculate the capacitance with:
- Permittivity (ε) = 8.85 × 10⁻¹² F/m (vacuum permittivity)
- Plate Area (A) = 50 cm²
- Separation Distance (d) = 0.5 cm
First, convert to SI units:
- Area: 50 cm² = 0.005 m²
- Distance: 0.5 cm = 0.005 m
$$C = \frac{8.85 \times 10^{-12} \times 0.005}{0.005} = 8.85 \times 10^{-12} \text{ F} = 8.85 \text{ pF}$$
Applications
- Electronic circuits
- Energy storage systems
- Filters and signal processing
- Touch screens
- Power factor correction