Total Excess Charge using a Coulomb Balance

In summary, when conducting a Coulomb Balance experiment, the total excess charge on a sphere with a conducting surface charged to 2,000,000V potential can be estimated using the equation V = q/R or C = 4πε0r. Spheres are often used in this experiment because they make the math easier. However, in either case, the value of r must be known.
  • #1
ZedCar
354
1

Homework Statement



If conducting a Coulomb Balance experiment, and a question asks to estimate the total excess charge on a sphere with a conducting surface charged to 2,000,000V potential.

Is there a specific equation I should be using to estimate this?

Thank you.

P.S. why are spheres used in such an experiment, and not some other shape?
 
Last edited:
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  • #2
ZedCar said:

Homework Statement



If conducting a Coulomb Balance experiment, and a question asks to estimate the total excess charge on a sphere with a conducting surface charged to 2,000,000V potential.

Is there a specific equation I should be using to estimate this?

Thank you.

P.S. why are spheres used in such an experiment, and not some other shape?

V = q/R
'cause they make the math easy.
 
  • #3
Is it not C = 4∏ε0r

(Sorry for large font, I was trying to obtain a small 0 beside ε!)
 
  • #4
ZedCar said:
Is it not C = 4∏ε0r

(Sorry for large font, I was trying to obtain a small 0 beside ε!)

Yes, sure. In either case though you have to know the value of r.

(I assume you got the right formula for C of a sphere.)
 
Last edited:
  • #5


I would first like to clarify that the Coulomb Balance is an experimental tool used to measure electric charge. It involves balancing the electrostatic force between two charged objects to determine the charge on one of the objects.

To estimate the total excess charge on a sphere with a conducting surface charged to 2,000,000V potential, you can use the equation Q = CV, where Q is the charge, C is the capacitance, and V is the potential. In this case, the capacitance of the sphere can be calculated using the equation C = 4πεr, where ε is the permittivity of the medium and r is the radius of the sphere. By plugging in the values for V and r, you can estimate the total excess charge on the sphere.

Spheres are commonly used in Coulomb Balance experiments because they have a uniform charge distribution and their shape allows for easy calculation of capacitance. Other shapes may have more complex charge distributions, making it difficult to accurately measure the charge using a Coulomb Balance. Additionally, the electrostatic force between two spheres is purely radial, making it easier to balance and measure compared to other shapes.
 

1. What is a Coulomb balance and how does it work?

A Coulomb balance is a scientific instrument used to measure the total excess charge on an object. It works by using Coulomb's Law, which states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. The balance measures the force between two charged plates and uses this to calculate the total excess charge on the object placed between them.

2. What is total excess charge and why is it important to measure?

Total excess charge refers to the overall amount of electric charge present on an object. It is important to measure because it can be used to determine the properties and behavior of the object, as well as its interactions with other charged objects. This information is crucial in many scientific fields, such as electrochemistry, materials science, and plasma physics.

3. What are some common applications of a Coulomb balance?

A Coulomb balance has a wide range of applications in various scientific fields. Some common uses include measuring the charge of particles in a plasma, determining the charge of a material's surface, and studying the electrical properties of materials. It can also be used in experiments involving static electricity, such as the Van de Graaff generator.

4. How accurate is a Coulomb balance in measuring total excess charge?

The accuracy of a Coulomb balance depends on various factors, such as the design and calibration of the instrument, the quality of the materials used, and external factors that may affect the measurements (e.g. humidity, temperature). Generally, modern Coulomb balances can achieve a high level of accuracy, with some instruments being able to measure charges as small as a single electron.

5. Are there any limitations or potential sources of error when using a Coulomb balance?

Like any scientific instrument, a Coulomb balance has its limitations and potential sources of error. These can include external factors affecting the measurements, such as stray electric fields or temperature fluctuations. Additionally, the accuracy of the balance can be affected by the size and shape of the object being measured, as well as the distance between the charged plates. It is important to carefully consider and control these factors when using a Coulomb balance to ensure accurate measurements.

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