A parallel plate capacitor with plate separation d is connected to a battery. Th
ID: 1527840 • Letter: A
Question
A parallel plate capacitor with plate separation d is connected to a battery. The capacitor is fully charged to Q Coulombs and a voltage of V. (C is the capacitance and U is the stored energy.) Answer the following questions regarding the capacitor charged by a battery. For each statement below, select True or False.
After being disconnected from the battery, inserting a dielectric with will decrease U.
After being disconnected from the battery, increasing d decreases V.
After being disconnected from the battery, decreasing d increases U.
With the capacitor connected to the battery, decreasing d increases C.
After being disconnected from the battery, inserting a dielectric with will decrease C.
After being disconnected from the battery, inserting a dielectric with will decrease V.
Explanation / Answer
formula for capacitence of the parallel plate capacitor is
C = eo A/ d
U = 1/2 CV^2
when dielectric inserted C' = k eo A/d
V'= V/k
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Ture
U' = 1/2 c' v'^2
= 1/2 ( k eo A/d) ( v/k)^2
= U/k
so After being disconnected from the battery, inserting a dielectric with will decrease U.
False because After being disconnected from the battery, increasing d increases V
Flase
True because capacitence is inversily proportional distance between the plates
False because C'= kC
True because V' = V/k