True or False and Why? a. If I slip a dielectric with kappa=2 into a capacitor t

Question

True or False and Why?

a. If I slip a dielectric with kappa=2 into a capacitor that holds a charge Q, the voltage will be 1/2 as big as before.

b. A capacitor has its air gap doubled and its area also doubled. The capacitance is unchanged.

c. Two capacitors differ only in the dielectric material that fills them. For the same voltage, the one with the higher dielectric constant holds more charge.

d. If I connect a battery to a parallel plate capacitor and then pull the plates apart, the charge on the capacitor will increase.

e. If the charge on one side of a capacitor is +Q, and the other side it is -Q, then the energy in the capacitor is Q2/C.

Explanation / Answer

(a) True.

Cnew/Coriginal = Kappa = 2

So, Cnew = 2*Coriginal

Now, Q = C*V

=> V = Q/C

Q will remain constant.

So, Vnew/Voriginal = Coriginal/Cnew = 1/2.

(b) True.

C = K*A/d

Both nominator and denominator are multiplied by '2'. So, 'C' will be constant.

(c) True.

Since, C = K*A/d

So, higher dielectric constant will have more capacaitance.

Now, Q = C*V

So higher will the value of C, higher will be the 'Q' for constant value of 'V'.

(d) False.

The charge will remain constant.

(e) False.

E = 0.5 C*V^2 = 0.5*Q^2/C

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

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