## College Physics (4th Edition)

(a) The sodium ions flow into the cell. (b) $F = 1.6\times 10^{-12}~N$
(a) The electric field is directed into the cell. Since the charge on the sodium ions is positive, the force exerted on the ions will be directed in the same direction as the electric field. Therefore, the sodium ions flow into the cell. (b) We can find the force exerted on the sodium ion: $F = E~q$ $F = (1.0\times 10^7~N/C)(1.6\times 10^{-19}~C)$ $F = 1.6\times 10^{-12}~N$