A Pair of Charged Conducting Plates Produces a Uniform Field $12,000 \mathrm {~N} / \mathrm { C }$

A pair of charged conducting plates produces a uniform field of $12,000 \mathrm {~N} / \mathrm { C }$ , directed to the right, between the plates. The separation of the plates is $40 \mathrm {~mm}$ . An electron is projected from plate $A$ , directly toward plate $\mathrm { B }$ , with an initial speed of $v _ { 0 } = 2.0 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$ . What is the speed of the electron as it strikes plate $B$ ? $\left( e = 1.6 \times 10 ^ { - 19 } \mathrm { C } , m _ { \text {electron } } = 9.11 \times 10 ^ { - 31 } \mathrm {~kg} \right)$

A) $2.1 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$
B) $1.5 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$
C) $1.2 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$
D) $2.4 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$
E) $1.8 \times 10 ^ { 7 } \mathrm {~m} / \mathrm { s }$