Capacitance Converter

Invented in 1745, the Leyden jar was one of the earliest forms of a capacitor. It consisted of a glass jar coated inside and out with metal foil, and was instrumental in early experiments with electricity.

Modern touchscreens work on the principle of capacitance. The screen has a grid of transparent conductors. Your finger, which is conductive, disrupts the electrostatic field at a specific point. The device detects this change in capacitance and registers it as a touch.

One Farad is such a large unit of capacitance that it's rarely seen in typical electronics. A one-farad parallel plate capacitor using a 1mm air gap would need plates with an area of over 113 square kilometers.

Supercapacitors, or ultracapacitors, can store thousands of times more energy than a standard capacitor, with capacitance values in the hundreds or thousands of Farads. While they don't have the energy density of batteries, they can charge and discharge almost instantly, making them useful for regenerative braking systems and providing quick bursts of power.

In electronic circuits, any two conductive surfaces near each other (like two adjacent traces on a circuit board) can act as an unintended capacitor. This 'stray capacitance' can affect circuit performance at high frequencies and must often be accounted for in complex designs.

Capacitors are fundamental components in electronic filters. They can block direct current (DC) while allowing alternating current (AC) to pass. This property is used to create filters that separate or remove specific frequency ranges from a signal.

Some high-power film capacitors have a 'self-healing' property. If a small short-circuit occurs through the dielectric, the immense local current vaporizes the thin metal film around the fault, effectively isolating it and allowing the capacitor to continue functioning.

Small ceramic capacitors are often marked with a three-digit code. The first two digits are the significant figures, and the third is the multiplier (power of 10), with the value in picofarads (pF). For example, a code '104' means 10 × 10⁴ pF, which is 100,000 pF or 100 nF.

The human body can act as a capacitor, storing static electric charge. Walking across a carpet can build up a charge, which then discharges as a spark when you touch a grounded metal object. This is known as electrostatic discharge (ESD) and can damage sensitive electronics.

The material between a capacitor's plates, known as the dielectric, significantly influences its capacitance. Different materials like ceramic, polymer film, or electrolytic solutions offer varying dielectric constants and properties, allowing for a wide range of capacitor types.

These sensors detect the presence of objects by measuring changes in capacitance. When an object enters the sensor's electric field, it changes the capacitance of the system, which can trigger a switch. They can detect both conductive and non-conductive materials.

A varactor is a special type of diode whose capacitance varies depending on the voltage applied to it. This property allows it to be used as a voltage-controlled capacitor in circuits like radio tuners and frequency synthesizers.

Electrolytic capacitors, a common type, can 'age' over time, especially when exposed to heat. This causes their capacitance value to decrease and their internal resistance (ESR) to increase, which can lead to equipment failure. This is a common reason for repairing older electronics.

Large capacitors are used in the power supply of audio amplifiers to act as energy reservoirs. They store charge and deliver it quickly to handle sudden musical peaks, preventing the voltage from dropping and ensuring clear, undistorted sound.

Medical defibrillators use a large capacitor to store a high-energy electrical charge. This energy is then delivered in a quick pulse to the heart to restore a normal rhythm during cardiac arrest.