Question

The magnetic induction at the centre of a coil made from a wire of length 44 m carrying a current of 0.5 A is nearly ____________.

Options

• 4.5 x 10^-6 Wb/m²

• 0.9 x 10^-6 Wb/m²

• 9 x 10^-6 Wb/m²

• 0.8 x 10^-6 Wb/m²

Answer 1

The magnetic induction at the centre of a coil made from a wire of length 44 m carrying a current of 0.5 A is nearly 4.5 x 10^-6 Wb/m².

Explanation:

`"B" = (mu_0 "I")/(2"r")`

`= (4pi xx 10^-7)/(2"r") xx 0.5`

` = pi xx 10^-7/"r"`

`"But"  44 xx 10^-2 = 2pi"r"`

`therefore "r" = (22 xx 10^-2)/pi`

`therefore "B" = (pi xx 10^-7 xx pi)/(22 xx 10^-2) approx 4.5 xx 10^-6  "Wb/m"^2`