Top panel: curves of normalised j_z recorded at the null during linear oscillatory reconnection (j₀ = 10⁻⁵ <  η) for a range of resistivity from η = 3 × 10⁻⁵ (black) through η = 1 × 10⁻³ (red) as per Table 1 (following maxima left to right, the curves go from higher to lower resistivity). Bottom panel: normalised Fourier power spectrum indicating the dominant period measured in the j_z(0, 0)-signals above. The vertical dashed lines indicate the expected period according to Eq. (7), which is consistent with the dominant periodicity bin in all cases.