Multiple Choice Questions (MCQs): Ampere's Law - JEE MCQ

If a current passes through any conductor, net charge through any section is zero. hence, electric field in the vicinity of the conductor is zero. We can observe using Biot and Savart law that the magnetic field at the axis of the cylindrical wire will be zero. Electric field at the axis of the wire cannot be zero otherwise the current through the wire cannot flow.
So statement 1 and 4 are correct.
 

Changes(if required):
Solution:
Sinθ=0 on any pt. on the axis of conductor carrying current
B=(μ_o/4Π)​​i(dlSinθ​/r²)

For a loop inside the hollow portion of the conductor, the current enclosed is zero until the loop is on the surface or inside the material of the conductor.
∴B_inside=0
For any loop outside, current enclosed by the amperian loop is not zero, hence the magnetic field is non-zero.
 

Ampere's law is similar to Gauss's law in electrostatics. 
Gauss's law correlates the surface integral of electric field E with charge q over a surface. 
Ampere's law co-relates the line integral of magnetic field B with current over a closed path.
 

According to ampere law for closed loop.as the net current in the loop is zero therefore answer is zero
Let upward direction of the current be positive in sign
therefore that for downward direction will negative
B.dl=u × current inside the loop
=u×(+I-I)
=0