Current.A moving charge is an object that changes position to one particular obsever.
The answer is 1575, I just took the Review.<span />
This problem uses the relationships among current
I, current density
J, and drift speed
vd. We are given the total of electrons that pass through the wire in
t = 3s and the area
A, so we use the following equation to to find
vd, from
J and the known electron density
n,
so:

<span>The current
I is any motion of charge from one region to another, so this is given by:
</span>

The magnitude of the current density is:

Being:

<span>
Finally, for the drift velocity magnitude vd, we find:
</span>
Notice: The current I is very high for this wire. The given values of the variables are a little bit odd
Answer:
d. Imaginary point through which the resultant force of gravity acts on an object
Explanation:
Gravity acting on all particle points of the object, no matter how small they are. As a combination, the center of gravity would denote a single point which substitutes for all the gravity forces on the object.