# Capacitors: find he charge for the new battery

• Alice7979
In summary, using the equation PE=CQ/2 and QV^2=CQ^2, the capacitor stores 0.12 C of charge when connected to a 9.0-V battery. The equation can be rearranged to solve for charge, and the precision of the given data is 2 significant figures.
Alice7979

## Homework Statement

A capacitor stores 7.9 x 10-2 C of charge when connected to a 6.0-V battery. How much charge does the capacitor store when connected to a 9.0-V battery?

PE=CQ/2

## The Attempt at a Solution

QV^2=CQ^2
(7.9 x 10-2)(6)/2 = Q(9)
C= .05 C

You are looking for an equation that relates capacitance, charge held on the plates, and the voltage across the plates.
1. Solve for capacitance.
2. Rearrange the equation and solve for charge.

I guess I made that more complicated

If you want to post the answer you came up with, I will see if it matches mine.

.1185 C

David Lewis
That's what I got. The precision of the given data is 2 significant figures, so I rounded to 0.12 C.

scottdave

## What are capacitors and how do they work?

Capacitors are electronic components that store electrical charge. They consist of two conductive plates separated by an insulating material, also known as a 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 stores energy in the form of electrical charge.

## How can I find the charge for a new battery using capacitors?

A capacitor can be used to measure the charge of a battery by connecting it in parallel with the battery. The voltage across the capacitor will increase as it charges, and the charge can be calculated by multiplying the capacitance (in Farads) by the voltage (in volts).

## What factors affect the charge of a capacitor?

The charge of a capacitor is affected by its capacitance, the voltage applied to it, and the dielectric material between the plates. Other factors that can impact the charge include temperature, humidity, and the surrounding electric field.

## How do I calculate the capacitance of a capacitor?

The capacitance of a capacitor can be calculated by dividing the charge (in Coulombs) by the voltage (in volts) across the plates. It can also be calculated by multiplying the permittivity of the dielectric material by the area of the plates and dividing by the distance between them.

## Why is it important to find the charge for a new battery using capacitors?

Finding the charge for a new battery using capacitors can help determine the health and performance of the battery. By measuring the charge, you can ensure that the battery is functioning properly and has the correct amount of charge for its intended use. This can also help with identifying any potential issues with the battery and prevent damage to other electronic components.

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