Two long wires are parallel to each other.The wires carry currents of different magnitudes.If the amount of current in each wire is halved,the magnitude of the force between the wires will be
A)twice the original force.
B)four times the original force.
C)the same as the original force.
D)half the original force.
E)one fourth the original force.

Question

Quizplus · Accepted Answer

The force between two parallel currents is directly proportional to the product of the currents in the wires. If the current in each wire is halved, the product of the currents becomes one fourth of its original value. According to Ampère's force law, the force is also directly proportional to this product, so the force becomes one fourth of its original value.

Two Long Wires Are Parallel to Each Other