# Understanding Capacitor Voltage in Relation to Ground

• Mzzed
In summary, if a capacitor is charged to 10V where the negative side is connected to ground (0V), when the capacitor is disconnected from the power supply on both the positive and negative sides; the negative side of the capacitor will still be 0V relative to the ground it was just connected to.
Mzzed
If a capacitor is charged to 10V where the negative side is connected to ground (0V), when the capacitor is disconnected from the power supply on both the positive and negative sides;

1) Will the negative side of the capacitor still be 0V relative to the ground it was just connected to?

2) Say the two sides of the capacitor are shorted. Charge would flow from the positive to the negative side of the capacitor, so does this mean the negative side of the capacitor will no longer be the same voltage as the ground it was connected to previously?

I'm asking this because I have components connected to the negative side of a capacitor that will likely break if the voltage rises too much above ground and although I think I know the answer to this I am really doubting myself now.

Any help is appreciated, thanks!

Mzzed said:
I'm asking this because I have components connected to the negative side of a capacitor that will likely break if the voltage rises too much above ground and although I think I know the answer to this I am really doubting myself now.

what other components ? show us the circuit

I was just generalising, the actual circuit is higher voltage and I don't have a diagram of it sorry. But for example I know the negative of a 1.5v battery is attached to the negative pin of the capacitor.

Mzzed said:
... I have components connected to the negative side of a capacitor that will likely break if the voltage rises too much above ground
If those components are lifted together with the capacitor and has no connection to the ground then they will remain on the voltage of that capacitor pin where they are connected, so they won't break down.

If those components are connected to the ground and the capacitor too, then the capacitor is not actually 'disconnected' from ground: it still connects through those components -> more details needed.

Mzzed
Rive said:
If those components are lifted together with the capacitor and has no connection to the ground then they will remain on the voltage of that capacitor pin where they are connected, so they won't break down.

If those components are connected to the ground and the capacitor too, then the capacitor is not actually 'disconnected' from ground: it still connects through those components -> more details needed.

ah ok, well despite that what happens in the situations 1) and 2) I mentioned before, ignoring any other components?

The absolute potential of a node depends on the rest of the circuit between the node and ground.

In circuits, we calculate voltage differences between two points. The absolute potential and the choice of where to connect ground ( if at all) is rarely significant.

If you are trying to understand circuits and ideal components, you're better off forgetting about ground and absolute potentials. Just remember that a voltmeter has two leads, not one.

jim hardy and Averagesupernova
Mzzed said:
ah ok, well despite that what happens in the situations 1) and 2) I mentioned before, ignoring any other components?
Mzzed said:
I was just generalising, the actual circuit is higher voltage and I don't have a diagram of it sorry.

You do realize you're asking people to guess at what you have in mind. Even in "Charades" you have to give better hints than that.

Do you have a voltmeter and a ladder ? Try it out. One experiment is worth a thousand expert opinions.

Mzzed
You are asking a theoretical question - about a real world situation? "the actual circuit is higher voltage"

I think if you sketch the scenario, and look at how you are going to charge a capacitor - you will find your answer.

Thanks guys, yeah my bad, should have included diagrams. I'll try testing myself and see if it makes sense.

## 1. What is a capacitor and how does it work?

A capacitor is an electronic component that stores electrical charge. It consists of two conductive plates separated by an insulating material, known as the dielectric. When a voltage is applied to the capacitor, one plate becomes positively charged and the other becomes negatively charged. This creates an electric field between the plates, which allows the capacitor to store energy.

## 2. What are the different types of capacitors?

There are several types of capacitors, including ceramic, electrolytic, film, and variable capacitors. Each type has its own unique properties and is designed for specific applications. For example, ceramic capacitors are small and inexpensive, making them ideal for use in electronic devices, while electrolytic capacitors have a higher capacitance and are commonly used in power supplies.

## 3. How is capacitance measured?

Capacitance is measured in farads (F), which represents the amount of charge that a capacitor can hold per unit of voltage. However, farads are typically too large of a unit for most capacitors, so they are often measured in microfarads (µF) or picofarads (pF). Capacitance can be calculated by dividing the charge on one plate by the voltage difference between the plates.

## 4. What factors affect the capacitance of a capacitor?

The capacitance of a capacitor is affected by several factors, including the distance between the plates, the surface area of the plates, and the type of dielectric material used. A larger distance between the plates results in a lower capacitance, while a larger surface area and a higher dielectric constant of the material increase the capacitance.

## 5. What are some common uses for capacitors?

Capacitors have a wide range of applications in electronics, including filtering out unwanted signals, smoothing power supply voltages, and storing energy in camera flashes and defibrillators. They are also used in timing circuits, audio equipment, and electric motors. In addition, capacitors are essential components in many electronic devices, such as computers, smartphones, and televisions.

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