# Please explain why the answer to the above question is zero.

aritra maity
42 Points
5 years ago

As conductor is connected with the cell, the potential difference across two paths (two possible paths i.e. one upside and one downside path) is same.
V= V2
I1R1=I2R2
I1dl1=I2dl(as resistivity and area of cross section same )

Now,
field, due to one path, is opposite due to another part. So magnetic field at the center is
$\frac{\mu }{4\pi }i1dl1\sin \Theta - \frac{\mu }{4\pi }i2dl2\sin \Theta$
[sin 90 = 1 , i1dl = i2dl2]
= 0 (proved)