729 small identical spheres each charged to an electric potential of 3 V combine to form a bigger sphere. The electric potential of the bigger sphere is:

Two capacitors C1 and C2 are charged to 100 V and 120 V respectively. When connected together in parallel with opposite polarity plates joined together, the net common potential is found to be zero. Therefore, which relation holds true?

Point charges -3Q, -q, 2q, and 2Q are placed, one at each corner of a square. The relation between Q and q for which the electric potential at the centre of the square is zero is: