Question

How many turns of wire must a coil have in order to induce a voltage of 10.5 volts when exposed to a changing magnetic flux with a rate of 0.0075 Wb/s?

Answer 1

The Faraday's law of electromagnetic induction (incorporating Len's law) gives the induced emf for a coil with `N` number of turns as:
`\xi_{"i"nd}=-N(d\Phi_B)/(dt) \qquad => \qquad | \xi_{"i"nd} | = N |(d\Phi_B)/(dt)|`.

`| \xi_{"i"nd} | = 10.5 V; \qquad (d\Phi_B)/(dt) = 7.5\times10^{-3} Wb.s^{-1}; \qquad N=?`

`N = (|\xi_{"i"nd}|)/(|(d\Phi_B)/(dt)|) = (10.5 V)/(7.5\times10^{-3}Wb.s^{-1})=1400` turns.