A 3.0g insulating ball carrying a charge of +2.0μC is suspended by a 0.50m light string from the ceiling. When a uniform horizontal electric field is switched on, the string makes an angle of 10∘ with the vertical and the ball remains at rest. What is the magnitude of the electric field?
a) 1.4×104N/C
b) 8.3×104N/C
c) 2.6×103N/C
d) 2.6×106N/C