Which statements are true for two oppositely charged, isolated parallel plates:

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.

1.Inserting a dielectric decreases U.
2.When the distance is doubled, C increases.
3.Increasing the distance increases the Electric field.
4.Inserting a dielectric increases Q.
5.Inserting a dielectric increases C.
6.When the distance is halved, Q stays the same.
7.When the distance is doubled, U increases.

Explanation / Answer

1) Inserting a dielectric decreases U - True

Reason - The capacitance increases with insertion of dielectric , for fixed charge, capacitance in inversely proportional to enegy (U) , so U decreases.

2) When the distance is doubled, C increases - False

Reason - C = keA / d - so if distance in increase, C should decrease.

3) Increasing the distance increases the Electric field - False

Reason - E = V/d so, increasing the distance should decrease the electric field

4) Inserting a dielectric increases Q - False  

Reason - charge remains fixed

5) Inserting a dielectric increases C - True

Reason = C = keoA / d where k is dielectric ,

6) When the distance is halved, Q stays the same - True

7) When the distance is doubled, U increases - True

Reason - as C decreases with increase in distance, so U increases.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.