Question

Lines of the magnetic field produced by a long straight wire carrying a current are:

Group of answer choices
A. circles that are concentric with the wire.
B. in the direction of the current.
C. radially inward toward the wire.
D. opposite to the direction of the current.
E. radially outward from the wire.

Answer 1

answer is a

Step-by-step explanation:

Answer 2

Answer: A) circles that are concentric with the wire.

Explanation: In order to explain this problem we have to take into account the Ampere law which is given by:

∫B*dl=μo*I where I is the current and μo the vacuum permeability.

So for any distance r from the wire the magnetic field is constant then we have:

B=μo*I/(2*π*r), this means that the magnetic field lines are circles concentric with the wire and they decrease as far the lines are from the wire.