The circuit shown in the figure is used to charge the capacitor C alternately from two current sources as indicated. The Switches  and  are mechanically coupled and connected as follows:        

For         ,        

(n = 0, 1, 2,…)          to  and  to

For        ,        

(n = 0, 1, 2,…)          to  and  to .

Assume that the capacitor has zero initial charge. Given that u(t) is a unit step function, the voltage  across the capacitor is given by