A uniform conducting wire of length 12a and resistance R is wound up as a current carrying coil in the shape of (i) an equilateral triangle of side a, (ii) a square of sides a, and (iii) a regular hexagon of sides a. The coil is connected to a voltage source V0. Find the magnetic moment of the coils in each case.
(i) For equilateral triangle of side a,
As the total wire length = 12a, so the no. of the loops
The magnetic moment of the coils m = nIA
As the area of the triangle is
Iii) For a square of sides a,
No. of loops n =
Magnetic moment of the coils m =nIA= 3I(a2) = 3Ia2
(iii) For regular hexagon of sides a,
No. of loops n =
Aera,
Magnetic moment of the coils m = nIA
, m is in a geometric series.