In this book it is written on pg $313$ in the last paragraph that Ohms law i.e. $R (constant)=\frac{\epsilon_{ind}}{I}$ is valid for induced current in a circuit. They define $R$ to be the sum of the resistance of all the resistive elements part of the circuit, $I$ to be the current and $\epsilon_{ind}$ to be the induced EMF. I have two doubts related to the meaning of the terms $I$ and $\epsilon_{ind}$.
- What current does $I$ represents? Does it represent induced or net current through the circuit? Suppose in a circuit there is a battery connected as well, the circuit is kept in a region where its magnetic flux changes. The battery and changing magnetic flux will both produce current. Does $I$ represent net current through the circuit i.e. the net sum of currently produced by battery and flux or just induced current?
- Around what loop is $\epsilon_{ind}$ calculated? There can be infinitely many closed lines along which we can calculate $\epsilon_{ind}$, then for which loop does $\epsilon_{ind}$ corresponds? See the diagram. The two black lines represent curves passing on the surface of a wire, the green and blue lines represent a loop inside the wire, and the red lines represent an uniform magnetic field that is increasing. I can calculate $\epsilon_{ind}$ along blue, green and also along the two black loops. But whose $\epsilon_{ind}$ is to be used in the formula?