An Electron Moves with a Speed Of $8.0 \times 10 ^ { 6 } \mathrm {~m} / \mathrm { s }$

Multiple Choice

An electron moves with a speed of $8.0 \times 10 ^ { 6 } \mathrm {~m} / \mathrm { s }$ along the $+ x$ -axis. It enters a region where there is a magnetic field of $2.5 \mathrm {~T}$ , directed at an angle of $60 ^ { \circ }$ to the $+ x$ -axis and lying in the $x y$ -plane.
Calculate the magnitude of the acceleration of the electron. $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } , m _ { e 1 } = 9.11 \times 10 ^ { - 31 } \right.$ $\mathrm { kg }$ )

A) $1.3 \times 10 ^ { 18 } \mathrm {~m} / \mathrm { s } ^ { 2 }$
B) $3.0 \times 10 ^ { 18 } \mathrm {~m} / \mathrm { s } ^ { 2 }$
C) $0 \mathrm {~m} / \mathrm { s } ^ { 2 }$
D) $1.3 \times 10 ^ { - 18 } \mathrm {~m} / \mathrm { s } ^ { 2 }$
E) $3.0 \times 10 ^ { - 18 } \mathrm {~m} / \mathrm { s } ^ { 2 }$