A Proton, Starting from Rest, Accelerates Through a Potential Difference $1.0 \mathrm { kV }$

Multiple Choice

A proton, starting from rest, accelerates through a potential difference of $1.0 \mathrm { kV }$ and then moves into a magnetic field of $0.040 \mathrm {~T}$ at a right angle to the field. What is the radius of the proton's resulting orbit? $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } , m _ { \text {proton } } = 1.67 \times 10 ^ { - 27 } \mathrm {~kg} \right)$

A) $0.080 \mathrm {~m}$
B) $0.14 \mathrm {~m}$
C) $0.11 \mathrm {~m}$
D) $0.17 \mathrm {~m}$