Another Electrical Field Question

[quickslant]

A test Charge of +1.0x10^-6 C is 40cm from a charged sphere of
3.2x10^-3 C.

a)how much work was required to move it there from a point 1.0x10^2m away from the sphere

b)how many electrons were gained or lost from the test object to create the charge?

Given: q1 = 1.0x10^-6 C q2 = 3.2x10^-3 C

Would i first need to calculate: Fe = k (q1)(q2)/r2 ? and then plug that into W = F (delta D)

 

[berkeman]

I don't think you can just plug it in -- You can integrate the force multiplied by delta-d as one charge is brought from the initial separation into the final configuration...

 

[quickslant]

i still don't understand how to do this question.. please someone help me !
=(

 

[EthanB]

I don't understand the question in part b.

Part a) recall that the work done by a conservative force is equal to the negative integral of force dot displacement.

 

[ND3G]

For part b) only concern yourself with the test charge. It is +1.0*10^-6 C.

How many electrons were gained or lost from the test object to create that charge?