Question

long straight wire carries 122 amps of current due wesr through a uniform external magnetic field of strength 3.0 mT directed 30 degrees west of north. a) How hard does the external field push one meter of the wire, and in what direction? b) What are the components of the magnetic field at a location 5.0 mm directly beneath the wire? (Don’t forget about the external field.)

the direction of the wire is due west

Answer 1

The current is in negative X direction (west)

The magnetic field is

a) The force vector on the wire per one meter is

The force magnitude is 0.317 N/m

And the direction is vertically downwards

b) The magnetic field due to the wire at r =5 mm below the wire is

The total magnetic field components in the y direction is

The magnetic field in the x direction is

Hence the magnetic field in the negative y or the SOUTH direction is 2.28 mT

The magnetic field in the negative x or the WEST direction is 1.5 mT