Question

The maximum strength of the earth's magnetic field is about 6.9 10-5 T near the south magnetic pole. In principle, this field could be used with a rotating coil to generate 60.0-Hz ac electricity. What is the minimum number of turns (area per turn

Answer 1

Number of turns,
`N=5* 10^5`

Step-by-step explanation:

Given that,

The maximum strength of the Earth's magnetic field,
`B=6.9* 10^(-5)\ T`

This field could be used with a rotating coil to generate 60.0-Hz ac electricity.

Let us assume that the coil must have to produce an rms voltage of 120 V and area per turn is 0.022 meter square.

`\epsilon=√(2) V_(rms)\\\\\epsilon=\sqrt 2* 120\\\\\epsilon=169.7\ V`

The emf induced in the coil is given by :

`\epsilon=NAB\omega\\\\\epsilon=2\pi NABf`

N is the number of turns

f is the frequency

`N=(\epsilon)/(2\pi ABf)\\\\N=(169.7)/(2\pi 0.022* 6.9* 10^(-5)* 60)\\\\N=2.96* 10^5`

or

`N=5* 10^5`

So, there are
`5* 10^5` turns in the coil.