The magnetic field at centre of a regular hexagonal coil of side L and carrying a current I is
1
\(\sqrt 3 \frac{{{\mu _0}I}}{{2\pi l}}\)
2
\(\frac{{\sqrt 3 \;{\mu _0}I}}{{\pi l}}\)
3
\(\frac{1}{{2\sqrt 3 }}\frac{{{\mu _0}I}}{{\pi L}}\)
4
\(\frac{1}{{\sqrt 3 }}\frac{{{\mu _0}I}}{{\pi L}}\)