How Do You Calculate the Charge on Spheres with Unequal Charges?

AI Thread Summary
To calculate the charges on two spheres that attract each other with a force of 1.2x10^-9 N and are 4 cm apart, one must use Coulomb's law, Fe = KQq/r^2. Given that one sphere has twice the charge of the other, the relationship can be expressed as Q = 2q. After converting the distance from centimeters to meters, the equation simplifies to finding q, which can then be doubled to determine the second charge. The discussion highlights the importance of proper unit conversion and confirms that solving for one charge provides the necessary information to find both. Understanding these calculations is essential for solving similar physics problems.
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Homework Statement


two charged spheres 4 cm apart attract each other with a force of 1.2x10^-9 . determin the magnitude of the charge on each if one has twice the charge (of the opposite sign) as the other.

Homework Equations



Fe = KQq/r^2

The Attempt at a Solution



well you are only given Fe and r, plus the info that Q is = to (2)q and k = 9.0x10^9 so I am stumped after this step

1.2x10^-9 = (9.0x10^9)(2)qq/16
 
Last edited:
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In your equation everything is a number except for q. Can you solve it for q? Also, you forgot to convert cm to meters.
 
could it possibly be that I am using the wrong equatiom? and should be using E(force intensity) = kq/r^2 instead of coulombs law??

edit: yes i forgot to convert haha good call..but yea the fact that I am finding two charges throws me off...so would just solving for one q give me the charge I am looking for, then just double it to get the 2nd charge?
 
Correct. Find q then double it. It is that simple.
 
aha well I've mised 2 of 2 classes on this unit so i can't believe it was that easy now that i see it ahhh well thanks alot
 
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