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?