Due to repolarisation outer surface of axonal membrane is positively charged due to

Due to repolarisation outer surface of axonal membrane is positively charged due to efflux of K⁺.

Depolarisation is quickly followed by a rise in permeability to K⁺. Within a fraction of a second,
K⁺ diffuses outside (efflux) the membrane due to opening of voltage gated K⁺ channels. It restores
the resting potential. This is called ‘repolarisation’. Na⁺ channel is inactivated. As a result, the influx
of Na⁺ ions into the axoplasm from the ECF is checked. This leads to the returning of axolemma
to the resting state (exit of potassium ions causes a reversal of membrane potential to negative inside).