# Using electric force to calculate number of protons

• dizzydani
In summary, the problem involved using electric force calculations to determine the number of protons in an unknown nucleus by comparing it to the charge of a hydrogen nucleus. The calculation resulted in a charge of -2.39x10^-19C for the unknown nucleus, but the main challenge was determining how many protons this charge represented. After realizing that the given distance was the diameter and not the radius, the solution was found to be carbon.
dizzydani
[SOLVED] using electric force to calculate number of protons

## Homework Statement

a hydrogen nucleus and a nucleus of an unknown atom are stationary, 5.0x10^-10m apart, the electric charge on the hydrogen nucleus is 1.6x10^-19C.
express the charge you have calculated for the unknown nucleus as a whole number multiple of the charge on the hydrogen nucleus, you may assume this number is the atomic number of the unknown nucleus, ie the number of protons

## Homework Equations

I used Fe= -ke Q1 Q2 / r^2

## The Attempt at a Solution

my calculation gave me the charge on the unknown nucleus to be -2.39x10^-19C
however, when i try to turn this into some whole number compared to 1.6x10^-19, i either get 1.5 or 0.6, neither of which are whole numbers.
please help with this part of the question, even if its just a nudge as to what on Earth is actually being asked...
neither integers nor any similar work appears in my coursebook and my tutor isn't returning my emails.

dizzydani said:
my calculation gave me the charge on the unknown nucleus to be -2.39x10^-19C

How? Data seems to be missing here.

full equation

okay, so using Fe = -Ke Q1 Q2 / r^2

Fe = 5.5x10^-9 N
-Ke = -9.0x10^9 Nm^2C^-2
Q1 = 1.6x10^-19C
r^2 = 6.25x10^-20m^2

Q2 = 5.5x10^-9 x 6.25x10^-20 / -9.0x10^9 x 1.6x10^-19

Q2 = -2.39x10^-19C

but the main part of the problem is the part where i have to use the 2 number for Q to tell how many protons Q2 nucleus has... i just arent sure where to start with that part

dizzydani said:
Fe = 5.5x10^-9 N
This was not previously mentioned.

r^2 = 6.25x10^-20m^2
How, with the given value of r=5.0x10^-10m?

ah-haa!

that was it, that was what was causing all my problems. i thought that because it said they were 5.0x10^-10m apart i thought that was the diameter, and that i wanted the square of the radius... i just calculated it all again and i get it now... its carbon...

thanks muchly

big hugs in cyberspace

## 1. How does electric force help in calculating the number of protons?

Electric force is a fundamental force of nature that acts between charged particles. Protons have a positive charge, and by measuring the strength of the electric force acting on them, we can determine the number of protons present in a given sample.

## 2. What is the equation used to calculate the number of protons using electric force?

The equation used is F = k * ((q1 * q2) / r2), where F is the electric force, k is the Coulomb's constant, q1 and q2 are the charges of the particles, and r is the distance between them.

## 3. Can electric force be used to calculate the number of protons in any type of sample?

Yes, electric force can be used to calculate the number of protons in any sample that contains charged particles. However, the accuracy of the calculation may vary depending on the type of sample and the setup of the experiment.

## 4. Are there any other methods besides using electric force to determine the number of protons?

Yes, there are other methods such as mass spectrometry, which can also be used to determine the number of protons in a sample. However, electric force is a commonly used and reliable method for this calculation.

## 5. How does the distance between charged particles affect the calculation of number of protons using electric force?

The electric force between two charged particles decreases as the distance between them increases. Therefore, if the distance is not accurately measured, it can affect the accuracy of the calculation. It is important to carefully measure and control the distance in order to get an accurate result.

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