Magnetic field of a current-carrying wire    

Right-Hand-Rule.

Point the thumb of the right hand in the direction of the current.

The tips of curled fingers will point in the direction of the magnetic field B.

Magnetic field of a current-carrying wire

B =( μo I)/ (2πr)

r     perpendicular distance to the wire in m 

Example

A long straight wire carries a current of 16 A.

The magnetic induction in a point is 4.0 x 10-5 T

Find the (perpendicular) distance  to the wire

B =( μo I)/ (2πr)

4.0 x 10-5 = ((4π x 10-7  )( 16)) / (2πr)

(2πr)( 4.0 x 10-5) = 64π x 10-7

 r = (64 x 10-7)/(8.0 x 10-5) =  0.08 m

Enable Notifications    OK No thanks