In a neon gas discharge tube ${\mathrm{Ne}}^{+}$ ions moving through a cross-section of the tube each second to the right is $2.9\times {10}^{18},$ while $1.2\times {10}^{18}$ electrons move towards left in the same time; the electronic charge being $1.6\times {10}^{-19}\mathrm{C},$ the net electric current is