## College Physics (4th Edition)

The kinetic energy of the electron when it leaves the space between the plates is $6.0\times 10^{-15}~J$
We can find the potential difference in the motion of the electron: $\Delta V = (\frac{3.0~mm}{12.0~mm})~(100.0~kV) = 25,000~V$ We can use conservation of energy to find the final kinetic energy $K_2$: $K_2+U_2 = K_1+U_1$ $K_2 = U_1-U_2 + K_1$ $K_2 = -\Delta V~q +K_1$ $K_2 = (-25,000~J/C)(-1.6\times 10^{-19}~C)+2.0\times 10^{-15}~J$ $K_2 = 6.0\times 10^{-15}~J$ The kinetic energy of the electron when it leaves the space between the plates is $6.0\times 10^{-15}~J$