Question

A short current element dl⃗ = (0.500 mm)j^ carries a current of 5.00 A in the same direction as dl⃗ . Point P is located at r⃗ = ( -0.730 m)i^+ (0.390m)k^. Find the magnetic field at P by current.

Also, - At a particular instant, charge q1 = 4.70×10−6 C is at the point (0, 0.250 m, 0) and has velocity υ⃗ 1=(9.20×105m/s)ι^. Charge q2 = −3.20×10−6 C is at the point (0.150 m, 0, 0) and has velocity υ⃗ 2=(−5.30×105m/s)j^.

At this instant, what is the magnetic force that q1 exerts on q2?