I just walked out of a physics test, and one of the questions was to the effect of:
You charge a parallel plate capacitor to 'Q', disconnect the battery, and double the distance between the plates. How does the potential difference (Voltage) change?
After some thought, I deduced that if Q remains the same and Q=CV (C=capacitance in farads), then V must double to maintain the same charge Q.
My reasoning is that by separating the plates, you are doing work on them. This energy must be stored somewhere, and since C cannot increase (In fact it is dropping) then V must increase by doubling.
The overall energy in the capacitor will increase according to U=C(V^2)/2, so the energy will double after accounting for the drop in capacitance.
Sound correct?
If I miss this question I don't have the luxury of an explanation as to why I missed it without going to some inconvenient office hours.
You charge a parallel plate capacitor to 'Q', disconnect the battery, and double the distance between the plates. How does the potential difference (Voltage) change?
After some thought, I deduced that if Q remains the same and Q=CV (C=capacitance in farads), then V must double to maintain the same charge Q.
My reasoning is that by separating the plates, you are doing work on them. This energy must be stored somewhere, and since C cannot increase (In fact it is dropping) then V must increase by doubling.
The overall energy in the capacitor will increase according to U=C(V^2)/2, so the energy will double after accounting for the drop in capacitance.
Sound correct?
If I miss this question I don't have the luxury of an explanation as to why I missed it without going to some inconvenient office hours.