Which statements are true for two oppositely charged, isolated parallel plates:
ID: 1596002 • Letter: W
Question
Which statements are true for two oppositely charged, isolated parallel plates: C=capacitance, U=stored energy (Q and -Q = charge on the plates). Note: Isolated plates can not lose their charge. True/ False
When the distance is halved, Q stays the same.
When the distance is doubled, U increases.
Inserting a dielectric increases Q.
When the distance is doubled, C increases.
Increasing the distance increases the Electric field.
Inserting a dielectric increases C.
Inserting a dielectric decreases U.
Explanation / Answer
Charge Q between the Plates Q = CV
Capaciatnce C = eo A/d
eo is permitivity of free space
A is area = pi r^2
d is distance between the plates
Volatge V = Ed
E is Electric field
Energy across the plates = U = 0.5 CV^2
--------------------
so Charge Q = eoA/d * E d = eo Eo A
this is does not depends on Distance d
hence even if d is halved, Q stays the same
When the distance is halved, Q stays the same. --True
----------------------------
as U = 0.5 CV^2
d doubles , means C halves by 2 and V enhaces by 2 timrs
so U also Remains same
When the distance is doubled, U increases is FALSE
----------------------------------
C = K Co
V = Vo/k
Thus
Q remains same
Inserting a dielectric increases Q. is FALSE
------------------------------------------
as C= eo A/d
if d is Doubled, C reduced by 2 times
thus
When the distance is doubled, C increases. is FALSE
-------------------------------
as E = V/d
if d is increased,
E reduces
Increasing the distance increases the Electric field. is FALSE
-------------
from C = K co
if K is inserted, C increases
Inserting a dielectric increases C. TRUE
-----------------------
as U = 0.5CV^2
k makes C to increrases and V to decreases
thus U reduces by k times
so
Inserting a dielectric decreases U is TRUE
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.