Question

What is the magnitude of the magnetic field at a distance R=1 m from a straight wire which carries an electric current I=1 A? A)1.99×10−7 N/(A·m) B) 1.99X107 T C) There is no magnetic field D)It depends on the direction of the current E) 7.5×104 T

Answer 1

Ans: (A)

Explanation:

We know when a current carrying wire carries a current I , the magnetic field at a distance R perpendicular to the wire is

where ,

Given , I= 1 A , R = 1 m

So magnitude of magnetic field is

Why others options are not correct:

(B & E) as from calculation we have power of 10^(-7) option B and E are not correct.

(C) as a current carrying wire creates a magnetic field , this option is not correct.

(D) If the direction of current changes direction of magnetic field changes but magnitude will not change. So this option is not correct.