Question

1.   A current of 30A flows north on a 5m long wire and a current of 50A flows south on a 5m long wire. The two wires are 3cm apart. Calculate the magnitude of the magnetic force between the two wires. 

Answer 1

$F=\frac{\mu_0 I_1I_2l}{4\pi r^2},$

$F=\frac{10^{-7}\cdot 30\cdot 50\cdot 5}{0.03^2}=0.83~N.$