- #1
dwach
- 2
- 0
Homework Statement
Two negatively charged objects repel each other with a measured force of 6.3 N when they are 0.5 cm apart. If the excess charge on one of the objects is caused by 8.3 x 10^22 extra electrons, use Coulomb's Law to calculate the number of excess electrons on the second object.
Homework Equations
F = k*(q1)*(q2) / r^2
1e = 1.602 * 10^-19 c
1c = 6.242 * 10^18 e
k = 9.0 * 10^9 N*m^2/c^2
The Attempt at a Solution
I calculated the excess charge to be:(8.3*10^22 e) * (1.602 *10^-19) = 1.3 * 10^4 c
I used this as q2 in the F = k*(q1)*(q2) / r^2 equation and rearranged to find that:
q1 = (F * r^2) / k*q2
q1 = (6.3N * 0.005m^2) / (9.0*10^9N*m^2/c^2)*(1.3*10^4c)
q1 = 1.3 * 10^-18
Since 1c = 6.242*10^18e, to find number of excess electrons i multiplied q1 by 6.242*10^18 = 8.1146 eSo is the number of excess electrons on the second object 8.1 ?