A constant potential difference of 12 V is maintained between the terminals of a

Question

A constant potential difference of 12 V is maintained between the terminals of a 0.25 mueF, parallel-plate, air capacitor.

a.) A sheet of Mylar is inserted between the plates of the capacitor, completely filling the space between the plates. When this is done, how much additional charge flows onto the positive plate of the capacitor?

b.) What is the total induced charge on either face of the Mylar sheet?

c.) What effect does the Mylar sheet have on the electric field between the plates? Explain how you can reconcile this with the increase in charge on the plates, which acts to increase the electric field.

Explanation / Answer

a) charge on plate, Q = C V

Qi = (0.25uF)(12) =3 uC  

after dielectric is inserted.

C = k c0 = 3.1 x 0.25 uF = 0.775 uF

Qf = (0.775)(12) =9.3 uC  

additional charge = Qf - Qi = 6.3 uC  

b) induced charge = 6.3uC  

c) field inbetween plates will not change.

as extra charge is accumulated on plates.

but charge of opposite sign induced on dielectric face.

such that effective charge will be same as befor.e

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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