Let's say we have a wire loop with resistance $R$ in a changing magnetic field. The changing field will induce an electric field and hence an emf $\mathcal{E}$ around the loop. The induced E-field is not conservative and we cannot assign an electric potential. Why then can we calculate the induced current using $\mathcal{E}=IR$ if $R$ is defined to be the ratio between the potential drop and the current? I have read this question, but I think charges only accumulate to create a potential when the circuit is incomplete, why can we assume that we can say the same thing even if the loop is closed?

  • $\begingroup$ Potential drop is a loose term indicating emf drop over a resitance. It has nothing to do with the potential we associate with conservative fields. $\endgroup$ – Lelouch Mar 7 '17 at 10:05

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