Capacitance: 0.00 pF
Charge: 0.00 nC
Voltage: 0.00 V
Energy: 0.00 nJ
Current: 0.00 μA
Time: 0.00 ms
Capacitor Formulas
C = ε₀εᵣ·A/d
Q = C·V | E = ½CV²
V(t) = V₀(1-e^(-t/RC))
Q(t) = Q_max(1-e^(-t/RC))
Q-V Curve
Charging Curve
Parameters
Applications of Capacitors
Touchscreen
Capacitive touchscreens use the human body's capacitance to detect touch. Each touch creates a change in capacitance that the device registers.
Camera Flash
Camera flash circuits charge a capacitor to high voltage, then discharge it quickly through the flash tube to produce a bright burst of light.
Power Supply Filtering
Capacitors smooth out voltage fluctuations in power supplies by storing charge during peaks and releasing during dips.
Audio Filters
Capacitors are essential in audio crossovers and filters, blocking DC while allowing AC signals of specific frequencies to pass.
Understanding Capacitors
Key Concepts
- Capacitance C is proportional to plate area A and inversely proportional to distance d
- Dielectric materials increase capacitance by reducing the effective electric field between plates
- Charging follows an exponential curve with time constant τ = RC
- Energy stored in capacitor: E = ½CV² = ½QV = Q²/(2C)
- Charge Q is directly proportional to voltage V: Q = CV
Dielectric Materials
| Material | Dielectric Constant (εᵣ) | Application |
|---|---|---|
| Air (εᵣ = 1.00059) | 1.00059 | Variable capacitors, RF circuits |
| PTFE/Teflon (εᵣ = 2.1) | 2.1 | High-frequency applications |
| Glass (εᵣ = 3.9) | 3.9 | High-voltage capacitors |
| Mica (εᵣ = 5) | 5 | Precision capacitors |
| Water (εᵣ = 80) | 80 | Not practical (conductive) |