L represents the element of the current carrying conductor that is in the magnetic field.
So anyway, this gives us 20 times 6-- 120 times 10 to the minus 4.
So the magnitude of the magnetic field there created by current 2 is equal to 6 times 10 to the minus 4 teslas.
The bottom side is out of the magnetic field so there is no force in there.
Explanation- Electromagnetic induction is a process by changing a magnetic field in a conductor, which induces a current in another conductor placed in nearby.
But you might not expect that the force between wires is used to define the ampere.