A wire of length l is bent in the form of an equilateral triangle and carries an electric current i. (a) Find the magnetic field B at the centre. (b) If the wire is bent in the form of a square, what would be the value of B at the centre?

Explanation

`A_0 = sqrt (((1)/(3))^2 - ((1)/(6))^2 `
`=l Sqrt((1)/(9) - (1)/(36) = l.sqrt((4-1)/(36) = l sqrt((1)/(12))`
`:. MO, MP, MQ = (l)/(3)xx(1)/(2) sqrt(1)/(3) = (1)/(6sqrt3)`
So, B at `M = 3(mu_oi)/(4pi). (36xx3)/(12) . (l)/(3) 2 [(1)/(2)] `
`= (27mu_oi)/(pil) along ox`
(b) Solve as above.