Question

A long, straight wire carries a current along the Z-axis. One can find two points in the X-Y plane such that

• A. All of the below
• B. the directions of the magnetic fields are the same
• C. the magnitudes of the magnetic fields are equal
• D. the field at one point is opposite to that at the other point.

Answer 1

The correct option is A All of the below

Solution: According to our problem, current is along Z axis

in long straight wire.

now suppose that if we have two points in $X-Y$ plane

then

CASE 1: If these two points are at same distance from Z axis

but in opposite directions i.e.(one is in $+ve$ and other is in $-ve$)

then they both have equal magnitude of magnetic field.

and also they have opposite fields due to different directions

Opt C and Opt D is correct.

CASE 2: If these two points are in same +ve direction

and in a parallel line then the direction of magnetic fields

are same.

Opt B is correct.

hence,

The correct opt : A