(a) A physics lab instructor is working on a new demonstration. She attaches two identical metal spheres with mass m = 0.180 g to cords of length L as shown in the figure. @ Both spheres have the same charge of 7.60 nC, and are in static equilibrium when 8 = 4.90, What is L (in m)? Assume the cords are massless. ( 3 m J (b) What If? The charge on both spheres is increased until each cord makes an angle of 8 = 9.80 with the vertical. If both spheres have the same electric charge, what is the charge (in nC) on each sphere in this case? nC L J