- #1
mb85
- 44
- 0
Of the charge Q initially on a tiny sphere, a portion q is to be transferred to a second, nearby sphere. Both spheres can be treated a particles. For what value of q/Q will the electrostatic force between the two parts have 1/4 of the maximum possible value?
q1=Q when the charge is transferred its Q - q
q2=0 becomes q after transfer
F = K(|q1||Q-q|)/r^2
dF(q)/dq = 0
0 = dF/dq = K/r^2 d/dq (qQ - q^2)
then Q - 2q = 0
so q = Q/2
so Fmax is 1/2
My question is, where do i apply the 1/4 of the max. value? I am rather confused. I thought it would just be 1/4 of the max.
any help would be appreciated. thanks.
q1=Q when the charge is transferred its Q - q
q2=0 becomes q after transfer
F = K(|q1||Q-q|)/r^2
dF(q)/dq = 0
0 = dF/dq = K/r^2 d/dq (qQ - q^2)
then Q - 2q = 0
so q = Q/2
so Fmax is 1/2
My question is, where do i apply the 1/4 of the max. value? I am rather confused. I thought it would just be 1/4 of the max.
any help would be appreciated. thanks.