The fact that electric forces can be added in this way is known as
superposition. It’s also worth noting that this is true for an infinite
number of charges; next would come F4-on-2, then F5-on-2, and so forth.Vector Alert
The electric forces are
vectors, so remember to
add them geometrically,
NOT algebraically.- Consider four equal, positive point charges that are situated at
the vertices of a square. Find the net electric force on a negative
point charge placed at the square’s center.
Here’s How to Crack It
Refer to the following diagram. The attractive forces due to the two charges on
each diagonal cancel out F 1 + F 3 = 0, and F 2 + F 4 = 0 because the distances
between the negative charge and the positive charges are all the same and the
positive charges are all equivalent. Therefore, the net force on the center charge is
zero.