node voltage

I wanna study about calculating the capacitance value using the graph Where can I study about it and here is the example graph for this

I have solved my question like that successfully with mesh analysis which the question wanted from me. But I am just curious that how can I calculate this circuit using nodal analysis? Here is my calculation: and here is the question of the circuit: I don't want the whole solution. I...

My mesh current equations: - 300*i1 + 500(i1 - i2) + 600*i1 = 0 - 200*i2 -25 + 13 + 500(i2 - i1) = 0 Since i1 is 25mA i2 can be found easily. However, equation 1 will yield 70mA while equation 2 will give 35mA for i2. What am I missing here? I would be very grateful if someone can point out...