The equivalent capacitance of the combination shown is :

Solution

Physics sir · 4 steps

Look at the right-hand wire first: it shorts the two vertical capacitors, so they drop out completely.

1. Name the nodes. The left terminal joins the left plates of both horizontal capacitors, so call that node A. The right terminal sits on the right vertical wire, which joins the top and bottom rails directly. So the whole right part of the circuit, top and bottom, is one node, B.
2. Shorted capacitors. Each vertical capacitor has its top plate on the top rail and its bottom plate on the bottom rail. Both rails are node B, so the potential difference across each one is zero. They store no charge and contribute nothing.
3. What remains. Only the two horizontal capacitors are left. Each one connects A to B, so they are in parallel.

   C_(eq) = C + C = 2C

4. So. The equivalent capacitance is 2C, option (d).

The idea to keep. Before combining anything, mark which points are joined by plain wire. A capacitor whose two plates sit on the same node has zero voltage across it, so remove it.

Answer from the NTA final answer key. Solution by PrepWiser.