Necessity to discharge capacitors in circuits

1. Mar 3, 2012

BluFoot

The problem statement, all variables and given/known data

1. Is it necessary to discharge the capacitors before starting the experiment in series? Why?

2. Is it necessary to discharge before starting the experiment in parallel? Why?

The attempt at a solution

For the first one, we connected 3 capacitors in series, and the second one we connected them in parallel.

This is what I've written in my report so far:

1. Yes it is. In series, all capacitors have a different voltage. If not discharged properly, the capacitors may have accumulated charge stored in them. This charge could be added to the current already flowing thought the circuit, thus tampering with the voltages.

2. It is not necessary to discharge a capacitor in parallel. Contrarily to capacitors in series, capacitors in parallel all have the same voltage. Therefore, even if charge accumulates, the voltage measured shouldn’t be affected.

Does that make sense?

2. Mar 3, 2012

phinds

since you give no description of the experiment, one can randomly choose and answer and then create a condition under which it would be correct.

If you want a helpful answer, give a helpful question. Just saying parallel and series is meaningless without knowing WHERE the elements are and what other elements are in the circuit.

3. Mar 3, 2012

BluFoot

Sorry, there was a 7V battery connected that had a wire going to the 3 capacitors, which connected to a switch then back to the battery. We were told to discharge the capacitors by simply taking a wire and putting one end on the positive side of the capacitor and the other on the negative side, allowing the charge to flow through and eliminating the remaining charge.

4. Mar 3, 2012

phinds

both experiments would have different results depending on whether or not you discharged the caps first, so I'd say yes, to get consitent results you should in both cases discharge first.