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## Main Question or Discussion Point

For a coil,

[tex]e=N\frac {d\Phi}{dt}[/tex]

Where [itex]e\;[/itex] is the instantaneous voltage driving the coil and [itex] \Phi\;[/itex] is the flux generated through the coil with N turns.

For a coil

[tex]\oint \vec B \cdot d\vec l =\mu N I \Rightarrow B=\mu N I \Rightarrow \Phi = BS=\mu N I S[/tex]

In the book

[tex]e=N\frac{d\Phi}{dt}\times 10^{-8}[/tex]

It said the multiplier factor depends on the system units. I have no idea how that [itex]10^{-8}\;[/itex] comes from. Please help.

Thanks

Alan

[tex]e=N\frac {d\Phi}{dt}[/tex]

Where [itex]e\;[/itex] is the instantaneous voltage driving the coil and [itex] \Phi\;[/itex] is the flux generated through the coil with N turns.

For a coil

[tex]\oint \vec B \cdot d\vec l =\mu N I \Rightarrow B=\mu N I \Rightarrow \Phi = BS=\mu N I S[/tex]

In the book

**Handbook of Transformer Design & Application by Flanagan**, page 1.7, it gives[tex]e=N\frac{d\Phi}{dt}\times 10^{-8}[/tex]

It said the multiplier factor depends on the system units. I have no idea how that [itex]10^{-8}\;[/itex] comes from. Please help.

Thanks

Alan