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Basic Equations

The basic fomulas are

$$\frac{v_1}{v_2} = \frac{N_1}{N_2} ,$$ (69)

and

$$\frac{i_1}{-i_2} = \frac{N_2}{N_1} .$$ (70)

The coefficient of coupling   is a number k defined by

$$k = \frac{M}{\sqrt{L_1L_2}} .$$

The coefficient of coupling is always in the range

$$0 \leq k \leq 1 .$$

Ohm's law reads

$$\begin{array}{rl} v_1 & = L_1 \frac{di_1}{dt} + M \frac{di_2}... ... v_2 & = M \frac{di_1}{dt} + L_2 \frac{di_2}{dt} . \end{array}$$ (71)

In this case the signs of the mutual (M) terms are positive; if the fluxes were opposing, these two terms would be negative.

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