Question

You found a brand new alloy, Alloyha, with density of 9000 kg/m^3!, to be used for wiring across telephone lines. You know it has the conductive properties, but need to ascertain the mechanical rigidity. As a basic test, the wire needs to be able to withstand 5000 N/m. Since it is a thin wire, it is unwise to load weights on top of the wire as it provides an uneven distribution of force. So instead, you decide to apply force through the use of magnetic fields at the International Space Station (so that force from gravity can be ignored). You bring a copper wire to exert a magnetic field onto the Alloyha wire which has 50mA (to the right). You place the copper wire 3m from the Alloyha wire. What current (direction and magnitude) do you need to apply to see if Alloyha is a good material for wiring across telephone lines? Please draw a schematic.

Answer 1

Solution:

Let the current flowing in the alloyha in the left direction, i.e., opposite to the copper wire, then the force per unit length applied by copper wire on the alloyha is given by

(1)

Given that:

Putting these valuese in equation (1), we find

(2)