Answer:
When we have capacitors in series, with capacitances c1, c2, ...., cn, the total capacitance can be obtained from the equation:
1/ct = 1/c1 + 1/c2 + .......
When we have capacitors in parallel, with capacitances c1, c2, ..., cn, the total capacitance can be obtained from the equation:
ct = c1 + c2 +......
Ok, in this case we have two branches, and in each branch we have two capacitors in series.
So the capacitance of each branch will be:
1/ct = 1/c + 1/c = 2/c
ct = c/2.
Now we can think that we have two capacitors in parallel, each one with capacitance c/2.
So the total capacitance is:
ct = c/2 + c/2 = c.
