(a) Write down the Biot-Savart law for the contribution to the magnetic flux density dB at position vector r relative to a current carrying element dl that has a constant

current I flowing through it. (b) Calculate the magnitude of the magnetic flux density: (i)at the centre of a conducting circular loop carrying a constant current I. Let L be the radius of the circle; (ii)at the centre of a conducting square loop carrying a constant current I. Let L be the distance from the centre to each side. You can write down, without proof, the magnetic flux density due to a straight finite length wire: (ii)at the centre of a conducting regular n-sided polygon carrying a constant current I. Let L be the distance from the centre to each side. You can write down, without proof, the magnetic flux density due to a straight finite length wire. Show that as n tends to infinity that this result reduces to your result for (i).