Step 1: Calculate the total charge before connection. Total charge \( Q_{total} = 15 \mu C - 3 \mu C = 12 \mu C\).
Step 2: Determine the final charges when connected by a wire. Since the potential becomes equal and the charge is distributed proportional to the radius of each sphere, the larger sphere \(S_1\) (radius \(3R/4\)) will acquire a larger fraction of the total charge: \[ Q_1 = \frac{3}{4} \times 12 \mu C = 9 \mu C, \] \[ Q_2 = \frac{1}{4} \times 12 \mu C = 3 \mu C. \]
In the given circuit, the electric currents through $15\, \Omega$ and $6 \, \Omega$ respectively are
