A parallel plate capacitor with adjustible plate separation d and adjustible are
ID: 1399334 • Letter: A
Question
A parallel plate capacitor with adjustible plate separation d and adjustible area A is connected to a battery. The capacitor is fully charged to Q Coulombs and a voltage of V Volts. (C is the capacitance and U is the stored energy.) Give all correct answers concerning a parallel-plate capacitor charged by a battery (e.g. B, AC, CDF).
A) After being disconnected from the battery, increasing the area A will increase V.
B) With the capacitor connected to the battery, increasing the area A will increase U.
C) With the capacitor connected to the battery, decreasing d increases C.
D) After being disconnected from the battery, increasing the area A will increase C.
E) After being disconnected from the battery, increasing d decreases V.
F) After being disconnected from the battery, increasing d increases U.
I need the correct answer in order to rate.
Explanation / Answer
A) after disconnecting Q is constant
then V = Q/C
by increasing A then C increasesthen automatically V decreases ............So A is False
B) U = 0.5*C*V^2
connected to battery V is constant ,by increasing A increases C
then U increases ............So B is True
C) V is constant....
C = eo*A/d.....by decreasing d,increases C....true
D) C = eo*A/d =
by increasing A ,then C increases....True
E) After disconnecting Q is constant
V = Q/C
as d increases then C decreases,thereby V increases...False
F) U = Q^/(2*C)
increasing d then C decreses,hence U increases....True
So true statements are BCDF