An ion has a specific charge of -3.5 × 107 C kg-1. It is held stationary in a vertical electric field on the surface of the Earth.
What are the magnitude and direction of the electric field?
2.80×10−7 V m−12.80 \times 10^{-7} \text{ V m}^{-1}2.80×10−7 V m−1 upwards
2.80×10−7 V m−12.80 \times 10^{-7} \text{ V m}^{-1}2.80×10−7 V m−1 downwards
3.57×106 V m−13.57 \times 10^6 \text{ V m}^{-1}3.57×106 V m−1 upwards
3.57×106 V m−13.57 \times 10^6 \text{ V m}^{-1}3.57×106 V m−1 downwards