ANSWER TRUE OR FALSE Two Plates which statements are true for two oppositely cha

Question

ANSWER TRUE OR FALSE

Two Plates 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. D Increasing the distance increases the Electric field. E Inserting a dielectric increases Q. a When the distance is halved, Q stays the same. When the distance is doubled, C increases. E Inserting a dielectric increases C. D When the distance is doubled, U increases. E Inserting a dielectric decreases U. Submit Answer Tries 0/15

Explanation / Answer

E = ½CV²
Q = CV

a) Increasing the distance increases the Electric field
capacitance goes down, charge stays constant, voltage goes up.
Field is V/m, with both voltage and distance going up, so field stays the same.
So the statement is false.

b) Inserting a dielectric increases Q.
Charge doesn't change.
The statement is false.
c) When the distance is halved, Q stays the same.
Q cannot change
So the statement is true.
d) When the distance is doubled, C increases.
The statement is false, C decreases.

e) inserting a dielectric increases C, which lowers V, since the charge can't change. E = ½CV². Since the V term is squared, the net energy goes down.
Check, assume dielectric constant doubles. C then doubles.
So the statement is true.

f) When the distance is doubled, U increases.
C = r(A/d)
is 8.8542e-12 F/m
r is dielectric constant (vacuum = 1)
A and d are area of plate in m² and separation in m
double distance, C is cut in half.
cut C in half, V doubles
E = ½CV²
halfing C cuts E in half, doubling V increases E by 4, so net is a doubling in energy.
So the statement is true.

g) Inserting a dielectric decreases U.
inserting a dielectric increases C, which lowers V, since the charge can't change. E = ½CV². Since the V term is squared, the net energy goes down.
check, assume dielectric constant doubles. C then doubles.
by Q = CV, voltage halfs
E = ½CV²
E '= ½(2C)(V/2)² = ½(½)(C)(V)²
E goes down
So the statement is true.

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