(a) A tiny ball of mass 0.6 g carries a charge of magnitude 8 nC. It is sus- pended by a thread in a downward electric field of intensity 300 N/C. What is the tension in the thread if the charge on the ball is (i) positive? (ii) negative? (b) A uniform electric field is in the negative x-direction. Points a and b are on the x-axis, a at x = 2 m and b at x = 6 m. (i) Is the potential difference Vb-Va positive or negative? (ii) If the magnitude of Vb-Va is 10^5 V, what is the magnitude E of the electric field?