Please Help! Thank you :) Coulomb\'s Law, as discussed in your lecture section a
ID: 1574143 • Letter: P
Question
Please Help! Thank you :)
Coulomb's Law, as discussed in your lecture section and in Walker, section 19.3, tells that electric forces are sensitive to two primary effects: (1) the magnitudes of the two interacting charges, and (2) the distance between them. While electric forces are directly related to the magnitudes of the charges, these forces are inversely related to the square of the distance between them. This is just like the distance dependence of Newton's universal law of gravitation, from Physics 100. F=kh@ 2. q102 Where q1 and Q2 are the two interacting charges, r is the separation distance between them, and k is a constant equal to about 8.99x 109 N m2 /C2. A. Consider two little spheres of the same negative charge, -Q, that are separated by 20 cm. If the force between them is 4.57 x 1021 newtons, how many excess electrons does each one have? (Remember that each charge unit of a Coulomb has 6.25 x1018electrons in it.)Explanation / Answer
A)
Q = magnitude of charge on each sphere = ?
r = distance between the charges = 20 cm = 0.20 m
F = force = 4.57 x 10-21 N
Using the equation
F = k Q2/r2
4.57 x 10-21 = (8.99 x 109) Q2/(0.20)2
Q = 1.43 x 10-16 C
number of excess electrons = n = (1.43 x 10-16) (6.25 x 1018) = 894